Patent Application
20250206666
Embodiments of the present disclosure generally relate to compositions of carbon-based structural units (CSUs) and methods of forming CSUs using the composition.
Coal currently serves an important role as an energy source but the increasing demand for renewable energy has reduced the production and consumption of coal in the United States of America (USA). Coal is carbon-rich, and its use in energy generation may affect atmospheric CO2 levels. The air pollution and global environmental issues associated with the combustion of coal have limited the continuous application of coal in energy production. Specifically, according to the Bureau of Safety and Environmental Enforcement (BSEE), global warming results from various greenhouse gas emissions is partly due to fossil fuel burning, such as the combustion of coal. Therefore, several studies are being conducted to create new non-energy and fuel opportunities for Wyoming coal.
Wyoming serves as one of the major producers of coal in the USA. Wyoming Powder River Basin (PRB) coal plays an important role in the Wyoming energy industry. However, renewable energy is slowly replacing the coal industry, causing the market price of coal to drop. Thus, to attract new investment through technological innovation and support coal mine operations, environmentally friendly methods to create new diversified coal products are needed. One concern is characterizing the eco-efficiency of char products, which includes life-cycle metrics. In addition, the worldwide demand for structural building materials is rising. Moreover, environmentally friendly building materials are desirable for enabling “green” building projects. Therefore, there is a need for improved carbon-based structural units (CSUs) derived from coal and methods of fabrication thereof.
In one embodiment, a composition is disclosed. The composition includes about 1% to about 80% pyrolysis char (PC), about 0.1% to about 35% coal deposits, extracts, and residual tar (CDER) materials, and about 0% to about 99% pitch material.
In another embodiment, carbon-based structural unit (CSU) is disclosed. The CSU includes a cured composition. The cured composition includes about 1% to about 80% pyrolysis char (PC), about 0.1% to about 35% coal deposits, extracts, and residual tar (CDER) materials, and about 0% to about 99% pitch material.
In yet another embodiment, a method includes extracting a coal extraction residue (CER) from coal; fabricating pyrolysis char (PC) and a coal deposits, extracts, and residual tar (CDER) material from the CER; sieving and milling the PC into milled PC; and mixing the pyrolysis char (PC) and the CDER material to form a composition.
So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, and may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
Embodiments of the present disclosure generally relate to compositions of carbon-based structural units (CSUs) and methods of forming CSUs using the composition. In one embodiment, a composition is described herein. In another embodiment, a CSU including a cured composition is described herein. In another embodiment, a method of forming a CSU from the composition is described herein.
The inventors have found new and improved methods for fabricating CSUs from pyrolysis char (PC) and coal deposits, extracts, and residual tar (CDER) materials. Briefly, raw coal is thermo-chemically converted to produce PC and CDER materials. The resulting PC and CDER material are then converted to CSUs.
The desire for environmentally-friendly materials, energy savings, and reduced energy consumption in building materials can be addressed by the building materials described herein. Building materials made with PC and CDER material have reduced density, increased strength, reduced thermal conductivity, and increased insulative properties when compared to conventional materials, such as clay bricks. These materials, through recycling/reuse and decreasing the amount of energy usage in fabrication, further lessens the environmental impact of the CSUs.
The use of headings is for purposes of convenience and does not limit the scope of the present disclosure. Embodiments described herein can be combined with other embodiments.
As used herein, a “composition” can include component(s) of the composition, reaction product(s) of two or more components of the composition, a remainder balance of remaining starting component(s), or combinations thereof. Compositions of the present disclosure can be prepared by any suitable mixing process.
Embodiments described herein generally relate to a composition and methods of forming a composition formed using pyrolysis char (PC) and coal deposits, extracts, and residual tar (CDER) materials. The composition may be used to form carbon-based structural units (CSUs).
The CSUs include PC, CDER materials. In some embodiments, the CSUs may include pitch materials. The CSUs include about 1% to about 80% PC, about 0.1% to about 35% CDER material, and about 0% to about 99% pitch material by weight. The CDER materials and pitch materials acts as a binder.
PC is a solid residue from a pyrolysis process of coal. The PC is pyrolyzed between about 600° C. and about 900° C. The grain size of the PC is about 0.05 mm to about 1.0 mm, such as about 0.25 mm to about 0.5 mm. The porosity of the PC is about 0.01% to about 0.025%. The average pore size of the PC is about 1 nm to about 2 nm. The specific surface area of the PC is about 200 m2/g to about 300 m2/g.
The CDER materials include tetralin insoluble (TI), deposit (De), distillation residue (DR), and residue (Re). The softening point for De is between about 200° C. and about 300° C. The softening point for TI is between about 200° C. and about 300° C. The softening point for DR is between about 80° C. and about 150° C. The pitch materials may include mesophase pitch from coal (MP (coal)), mesophase pitch from naphthalene (MP (naphthalene)), or coal tar pitch (CTP).
The CSUs have a compressive strength of about 10 MPa to about 120 MPa. The CSUs have a flexural modulus of rupture between about 3 MPa and about 6 MPa. The average modulus of rupture of concrete is 3.01 MPa, thus, the CSU is about 50% higher than concrete. The average split tensile strength of the CSU is about 4 MPa to about 6 MPa. The average split tensile strength of concrete is about 2.58 MPa, thus, the CSU is about 235% higher than the concrete.
The average density of the CSUs is from about 0.5 g/cm3 1.5 g/cm3. Conventional clay bricks have a density of about 2.18 g/cm3. By decreasing the density of the CSUs as compared to conventional clay bricks, the monetary cost and environmental cost of transporting building materials may be decreased.
The CSUs have a thermal conductivity from about 0.1 W/m·K to about 0.5 W/m·K. Conventional clay bricks typically have a thermal conductivity value between about 0.5 W/m·K and about 1.0 W/m·K. A low thermal conductivity value indicates an increased ability to provide insulation properties. The CSUs have a lower thermal conductivity than conventional clay bricks, thus making them preferable in terms of insulation qualities in construction projects.
At operation 102, a pyrolysis char (PC) and a coal deposits, extracts, and residual tar (CDER) material are obtained from the CER. The CDER may be a solvent extracted from the coal. The solvent extraction process may use tetralin as the solvent for coal refining. In some embodiments, one or more reactors are loaded with the coal. The reactors are heated using an oven at a temperature of about 500° C. to 1000° C. A high-performance liquid chromatography (HPLC) pump is primed with tetralin and the system is pressurized to about 200 psi to about 300 psi with argon. A specific rate of tetralin is flowed through the reactors when the temperatures in the extract lines rise above about 500° C. to 1000° C. The tetralin flow is stopped after about 2 hours to about 6 hours under the temperature and the reactors start to cool down. Argon is used to remove the tetralin from the extraction lines. The argon is blown out of the extract lines to remove the remaining tetralin after the temperature of the extraction lines drops to about 100° C. to about 150° C. The residue (Re) remaining in the reactors is collected.
The Re is washed with toluene at room temperature and the remaining tetralin is removed, leaving tetralin insoluble (TI) material. The TI material is dried in a vacuum oven. Distilled residue (DR) is separated from the remaining tetralin. In one embodiment, the DR is separated from tetralin using a rotary evaporator. The deposit (DE) dissolved in the acetone solution from the system wash is solidified. As a result, four solid products can be obtained by dissolving coal in tetralin at elevated temperature and pressure: (1) the residue of undissolved coal (Re); (2) deposit (De), which is the least soluble dissolved material; (3) tetralin insoluble (TI), which precipitates at room temperature; and (4) distillation residue (DR), which is soluble at room temperature. A CDER material includes the four solid products Re, De, TI, and DR. In one embodiment, the PC and CDER material are manufactured at temperatures between about 700° C. and about 900° C.
At optional operation 103, the CDER material is heat-treated to form a heat-treated CDER. Heat treating the CDER materials may increase the content of heavy molecular weight components, improving the ability of CDER materials to act as a binder material. The heat-treatment occurs between 400° C. and 500° C. Heat-treating the CDER materials may cause volatilization of low molecular mass constituents of the pitch and polymerization and condensation reactions of the hydrocarbons. In addition, hydrogenation, fragmentation, alkylation or dehydrogenative polymerization may occur during heat-treatment. Thermal cracking of the aliphatic side group at the a-position in the aromatic molecules may result in the free radicals. These free aromatic radicals may react with each other to produce aryl-aryl linkages and then build up the polyaromatic molecules to form a carbonaceous mesophase.
In some embodiments, the CDER material is pressure heat-treated to form pressure heat-treated CDER (P&H treated CDER). P&H treated CDER materials may increase the aromatic index and the content of heavy molecular weight components in the CDER materials. The treatment may be conducted using an electrical strip reactor. During the treatment, an applied pressure of about 2 MPa to about 6 MPa is maintained at about 400° C. to about 500° C. for about 3 hours to about 10 hours in nitrogen environment. The heating rate is about 2.5° C./min to about 7.5° C./min. After the completion of heat treatment, the heater is turned off and left for about 6 hours to about 18 hours before cooling to room temperature. The CDER materials melt at this temperature, and volatile materials evaporate. After cooling, they form an integrated part that is ground with marble mortar and pestle to make fine particles.
In some embodiments, the PC is sieved and milled to form milled PC. In one embodiment, the PC is milled using a ball mill. In another embodiment, the PC is mixed with binders and milled to form the milled PC. The milled PC may be sieved and dried. The milled PC may have a diameter of less than about 35 μm. A ball mill machine may be used to grind the PC to obtain particle sizes less than 40 μm (e.g., using a #400 sieve). Stainless steel balls, about 10 mm and 20 mm in diameter, are placed inside a drum during the grinding process. The ball milling may be conducted for 20 hours to about 28 hours at a speed of 25 rpm to about 75 rpm in one directional rotation. Greater than 99% of the char powder passed through the sieve.
At operation 104, the PC and CDER material are mixed to form a CSU mixture. The PC and CDER materials are mixed at a ratio of about 1:1 to about 1:4 CDER material to PC. In some embodiments, The PC and CDER material are mixed with a pitch material to form the CSU mixture. The CSU mixture includes about 1% to about 80% PC, about 0.1% to about 35% CDER material, and about 0% to about 99% pitch material by weight. In some embodiments, manually ground pith material, i.e., mesophase pitch, is ball-milled with about 600 gm of this PC to mix evenly for 20 hours to about 28 hours at a speed of 25 rpm to about 75 rpm. After that, the mixture is oven-dried at a temperature of 150° C. for 24 hours before storing it in an air-tight container.
At operation 105, the CSU mixture is molded to form CSUs. In some embodiments, the mixture is molded under pressure. The CSU mixture may be molded under an applied pressure of about 50 MPa to about 500 MPa. A 50-ton capacity pressing equipment may be used to apply the pressure on the CSU mixture.
At optional operation 106, the CSUS are oxidized and carbonized. In an oxidation stabilization process, the CSU is first heated to about 200° C. to about 300° C. in an air atmosphere at a rate of 0.25° C./min to about 1.5° C./min and held at this temperature for 12 hour to about 20 hours. The oxidation stabilization process enables volatile contents in the mesophase pitch to be released in a low manner to mitigate the foaming risk. In a carbonization process, the CSU is heated to a higher temperature, about 600° C. to about 1000° C., at a rate of about 1.5° C./min to about 4.5° C./min and held at this temperature for about 0.5 hours to about 3 hours. The carbonization process may occur in an argon atmosphere.
Embodiments of the present disclosure also generally relate to uses of the compositions described herein. Compositions described herein can also be used for various applications.
Illustrative, but non-limiting, applications include concrete masonry units such as cinder blocks, breezeblocks, hollow blocks, concrete blocks, construction blocks, Besser blocks, clinker blocks, among other concrete masonry units.
The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use embodiments of the present disclosure, and are not intended to limit the scope of embodiments of the present disclosure. Efforts have been made to ensure accuracy with respect to numbers used but some experimental errors and deviations should be accounted for.
The Brunauer-Emmett-Teller (BET) analysis is performed using QUADRASORB evo surface area and pore size analyzer. The BET analysis was performed using ASTM D6556.
The x-ray diffraction (XRD) analysis is performed using a Ragku Smartlab diffractometer with a copper (Cu) potassium (Ka) source, operated at 44 kV and 44 mA with an angle of reflection of 2-theta (2θ) varied between 10° and 90°.
The Fourier Transform Infrared Spectroscopy (FTIR) is measured using a Nicolet iS50 FTIR spectrometer from Thermo Scientific.
The Scanning Electron Microscopy (SEM) is measured using FEI Quanta 250 Conventional SEM.
The thermogravimetric analysis (TGA) is performed using TGA 5500 discovery series of TA instruments.
The nuclear magnetic resonance (NMR) is performed using Bruker Avance III spectrometer.
Proximate analysis is performed using ASTM D7482.
Ultimate analysis is performed using ASTM D4239 and D5373.
The compressive strength of the CSUs is measured using a Zwick/Roell Z020 compression testing machine. The compressive strength of the CSUs is measured using ASTM C39.
The density is calculated from the measured sample geometry and mass after carbonization.
Thermal conductivity is measured using Hot Disk TPS 1500. The thermal conductivity of the CSUs was measured using ISO 22007-2.
The flexural strength of the CSUs is measured using a Zwick/Roell Z020 compression testing machine. The flexural strength of the CSUs is measured using ASTM C78.
The split tensile (Brazilian) tests are conducted using Zwick/Roell Z020 compression testing machine through a force-controlled test. A 20-kN load cell with an extensometer is used with a loading rate of 200 N/min. The split tensile (Brazilian) tests are conducted using ASTM D3967.
Table 1 shows a summary of the chemical composition of a pyrolysis char (PC). The PC was pyrolyzed at about 850° C., with a yield rate of about 46.3%. The yield rate is the ratio of the total amount of PC obtained to the total amount of raw coal used. The dominant material in the PC is carbon, while the metal contents are low (e.g., less than 15 mg of metal per kg of PC; e.g., 15 ppm). The metal contents of the PC satisfy multiple standards, including: the European Union Restrictions of Hazardous Substances (RoHS) Direction (less than 1,000 ppm of arsenic, chromium, copper, lead, mercury, and selenium; less than 10,000 ppm for cadmium); the Federal Hazardous Substances Act (FHSA), C.F.R. Title 16, Part 1500.17 (limits lead content for household products to less than 600 ppm of the total weight); ASTM F693-17 (sets maximum value for surface coatings and substrates included as part of a toy for arsenic at less than 25 ppm, cadmium at less 75 ppm, chromium at less than 60 ppm, lead at less than 90 ppm, mercury at less than 60 ppm, and selenium at less than 500 ppm); and the Consumer Product Safety Act (CPSA), C.F.R. Title 16, Part 1303 (sets maximum lead content in paints and surface-coating materials for children's products and general consumer products at 90 ppm). Thus, the PC used to form the carbon-based structural units (CSUs) are demonstrated as safe for use in commercial building applications.
Table 2 shows a summary of the composition of the CDER materials. The composition of the CDER materials is measured using ultimate analysis and proximate analysis. Solvent extraction in the coal extraction process occurs at low temperatures, such that the solvent extraction retains much of the oxygen in the coal. Carbon and oxygen are the dominant elements in the CDER materials.
The sulfur content within the CDER materials is the lowest of all the elemental components at less than 0.5 wt %. Low sulfur content is environmentally friendly due to the low emission of sulfur-related compounds during thermal treatment. The nitrogen content was relatively low, varying from 1.49 wt % to 2.22 wt % with an average value of 1.8 wt %. The oxygen content presents larger variations, from 7.89 wt. % to 21.18 wt %. The DR possesses the highest carbon content and the lowest oxygen content, followed by deposit (De), tetralin insoluble (TI), and residue (Re). Compared to raw coal, the four composites of CDER material show an increasing carbon content ratio attributing to the extraction process. According to the proximate analysis for CDER materials, DR has the lowest fixed carbon content and the highest volatile content. De has the highest fixed carbon content. TI shows the highest ash content. Re has the lowest volatile content and relatively higher fixed carbon and ash content.
The DR shows more aliphatic C—H groups than other CDER materials. The TI and De samples have more oxygen-rich groups than the Re. In addition, the De, TI, and DR samples present relatively more aromatic groups than the Re.
The TGA indicates the temperature at which volatiles are liberated. The generation of volatiles during foaming generally acts as bubbling agent and creates a porous structure. TGA is conducted in a nitrogen atmosphere. Heating rate for MP (coal), deposit (De), and TI is set at about 10° C./min. The heating rate is set at 5° C./min for coal tar pitch (CTP) and DR, due to their lower softening points and higher content of volatile matters.
The aliphatic protons with different δ values in other commercial pitch materials may be attributed to the hydrogen on the α-carbon attached to an aromatic ring (Hα, δ=2-4.5 ppm), the hydrogen on β-carbon attached to an aromatic ring (Hβ, δ=1.1-2 ppm), and the hydrogen on γ-carbon attached to an aromatic ring (Hγ, δ=0.5-1.1 ppm. The aromatic protons can be classified into uncondensed aromatic hydrogen (HarU, δ=6.5-7.2 ppm) and condensed aromatic hydrogen (HarU, δ=7.2-9.5 ppm). The ratio of Hal to Har of the liquid CTP, MP (coal), De, TI and DR are 0.22/1, 0.91/1, 4.3/1, 6/1, and 5.2/1, respectively. The analyzed CDER materials (De, TI, and DR) have predominance of aliphaticity over aromaticity.
Table 5 is a summary of the heat treating experiments for De and TI. Heat treating the CDER materials may increase the content of heavy molecular weight components, improving the ability of CDER materials to act as a binder material. The heat-treatment occurs between 410° C. and 450° C. Heat-treating the CDER materials may cause volatilization of low molecular mass constituents of the pitch and polymerization and condensation reactions of the hydrocarbons. In addition, hydrogenation, fragmentation, alkylation or dehydrogenative polymerization may occur during heat treatment. Thermal cracking of the aliphatic side group at the a-position in the aromatic molecules may result in the free radicals. These free aromatic radicals react with each other to produce aryl-aryl linkages and then build up the polyaromatic molecules to form a carbonaceous mesophase.
Based on the results from the 1H and 13C NMR spectra, all the coal extractions exhibit high aliphaticity and relativity low aromaticity, while the MP exhibits an opposite behavior. Therefore, the coal extractions can be heat-treated to improve their aromaticity before being used as binder materials. During the heat-treatment process, the pressure inside of the electric furnace is at the ambient pressure. The heat-treatment is carried out at a specific temperature for 10 hours. The gas flow rate of argon was about 100 ml/min.
The aromaticity indices of De, TI and heat-treated products can be calculated using absorbance values at wavenumbers of 3050 cm−1 and 2920 cm−1 given by Equation (1):
Where h3050 is the peak height of aromatic C—H stretching alkane at a wavenumber of about 3050 cm−1, and h2920 means the peak height of aliphatic C—H stretching alkane at a wavenumber of about 2920 cm−1.
The bending aromatic C—H to stretching cyclic alkane C═C peak intensity ratio is used to reflect the condensation degree of polycyclic aromatic hydrocarbons. The condensation degree of polycyclic aromatic hydrocarbon of De, De-410, De-430, and De-450 are 0.65, 0.97, 0.98, and 1.1, respectively. These demonstrate that the condensation degrees of the heat-treated CDER materials increase with increasing the heat-treatment temperature. De-450 shows the highest condensation degree than those of DE-430 and DE-410.
Table 6 is a summary of the composition of CDER materials, heat-treated CDER materials, and other commercial pitch materials. The compositions include untreated De (De); 410° C. heat-treated De (De-410); 430° C. heat-treated De (De-430); 450° C. heat-treated De (De-450); untreated TI (TI); 410° C. heat-treated TI (TI-410); 430° C. heat-treated TI (TI-430); 450° C. heat-treated TI (TI-450); and untreated MP (MP). The TGA test includes: the temperature ramps from room temperature to 110° C. in a nitrogen atmosphere and the isothermal time is 50 mins. The ramp rate is 5° C./min. This process can be used to estimate the moisture content of the CDER material. Then, the temperature ramps from 110° C. to 950° C. at the ramp rate of 30° C./min. The CDER material is held at 950° C. for 5 mins. After that, temperature decreases from 950° C. to 600° C. at the ramp rate of 10° C./min. Lastly, the purge gas is changed to air. Temperature increases from 600° C. to 750° C. at the ramp rate of 10° C./min, and the isothermal time is 50 mins.
Comparing De and heat-treated De, heat-treated De significantly increases the fixed carbon content from 55.9% of De to 72% of De-410. However, due to the small temperature difference, a large difference in fixed carbon contents for De-410, De-430, and De-450 is not observed. For TI and heat-treated TI, the fixed carbon content increases from 33.2% to 46.72%. Among them, TI-430 exhibits the highest fixed carbon content of 46.72%. The fixed carbon content for MP (coal) is about 85.9%, which is higher than that of De, heat-treated De, TI, and heat-treated TI. The ultimate analysis results indicate that the fixed carbon content increases with heat-treatment for De and TI. Furthermore, the C/H ratio increases from 14.58 of De to the highest ratio 21.27 in the heat-treated De-450. For TI and heat-treated TI, the ratios of C/H for TI, TI-410, TI-430, and TI-450 are 12.28, 17.7, 23.74, and 21.98, respectively. TI-430 shows the highest C/H ratio. The C/H ratio of MP (coal) is around 23.16, similar as the heat-treated De-430.
Pressure heat-treating (P&H treating) CDER materials may increase the aromatic index and the content of heavy molecular weight components in the CDER materials. The treatment is conducted using an electrical strip reactor. During the treatment, an applied pressure at about 4 MPa is maintained at 430° C. for about 5.25 hours in nitrogen environment. The heating rate is 5° C./min, and it takes around 82 minutes to reach 430° C. After the completion of heat treatment, the heater is turned off and left for 12 hours before cooling to room temperature. Due to the treatment, weight losses of 21.0% and 27.6% are observed for De and TI, respectively. The CDER materials melts at this temperature, and volatile materials evaporate.
For the untreated TI, when the temperature reaches at around 233° C., there is only about 3% of weight loss due to volatilization or decomposition of low molecular weight pitch components. The major weight loss is observed between 300° C. and 700° C. with the maximum decomposition rate at 512° C. which may be due to decomposition of the heavy molecular weight components. However, P&H treated TI has no significant weight loss before 500° C. as all the volatile matters should have already been volatilized during the P&H treatment. The major weight loss is observed between 500° C. and 850° C. with the maximum decomposition rate at 820° C. A residue weight of approximately 80% for P&H treated TI is obtained, whereas only 3.5% residue is obtained for untreated TI at 950° C. Therefore, to proceed with the P&H treated De and TI for carbonization, a temperature higher than 500° C. is needed. After carbonization at 900° C., less micro-cracks are found in the CSUs prepared with P&H treated CDER materials due to lesser weight loss.
Table 7 is a summary of the aromaticity index of the CDER materials.
Table 8 is a summary of the composition of CDER materials, heat-treated CDER materials, P&H treated CDER materials, and other commercial pitch materials. The compositions include PC (Char); untreated De (De); heat-treated De (DeH-treated); P&H treated De (DeP&H-treated); untreated TI (TI); heat-treated TI (TIH-treated); P&H treated TI (TIP&H-treated); and untreated MP (MP).
Table 9 is a summary of the thermal and mechanical properties of carbon-based structural units (CSUs). The CSUs include a 100 MPa pressing pressure/700° C. carbonization temperature sample (1); a 100 MPa pressing pressure/700° C. carbonization temperature sample (2); a 200 MPa pressing pressure/700° C. carbonization temperature sample (3); a 200 MPa pressing pressure/700° C. carbonization temperature sample (4); a 100 MPa pressing pressure/900° C. carbonization temperature sample (5); a 100 MPa pressing pressure/900° C. carbonization temperature sample (6); a 200 MPa pressing pressure/900° C. carbonization temperature sample (7); a 200 MPa pressing pressure/900° C. carbonization temperature sample (8); and a 400 MPa pressing pressure/700° C. carbonization temperature sample (9); MP (coal) is mixed with PC at a mass ratio of 1:2 to form a pitch mixture. The pitch mixture is ball milled, dried, and pressed into a CSU at a pressure from 100 MPa to 200 MPa. The tablet samples are thermally treated. In an oxidation stabilization process, the CSU is first heated to 240° C. in an air atmosphere at a rate of 1° C./min and held at this temperature for 16 hours. In a carbonization process, the CSU is heated to a higher temperature, about 700° C. to about 900° C., in an argon atmosphere at a rate of 3° C./min and held at this temperature for about 1 hour.
Higher pressing pressure slightly increases the density and thermal conductivity of the CSUs. The compressive strengths of the CSUs are 42.7 MPa for CSU pressed at 100 MPa and 85.6 MPa for the CSU pressed at 200 MPa pressing pressures. Hence, higher pressing pressure significantly increases the compressive strength of the CSU products. In contrast, increasing the pressing pressure from 200 to 400 MPa does not significantly increase the compressive strength (from 85.6 MPa to 91.5 MPa or only 6.4% improvement). In addition, increasing the pressing pressure from 200 to 400 MPa increases the thermal conductivity by 52.4%, thus reducing insulative properties of the CSU.
The CSU carbonized at 900° C. has higher thermal conductivity values of 0.217 and 0.241 W/m·K compared to that of the CSU carbonized at 700° C., indicating that a lower carbonization temperature has increased insulation properties. The thermal treatment and carbonization slightly decrease the density. The compressive strengths of the CSU carbonized at 900° C. are 89.1 MPa for the CSU pressed at 100 MPa and 109 MPa for the CSU pressed at 200 MPa.
Increased carbonization temperature increases the compressive strength of CSU. Compared to 700° C. carbonization temperature, the higher carbonization temperature of 900° C. yields higher compressive strength. However, a temperature higher than 900° C. may not necessarily increase the compressive strength because higher temperature results more graphite and may weaken the mesophase pitch binding.
Table 10 is a summary of the thermal and mechanical properties of CSUs with a MP:PC mass ratio of 1:3. The CSUs include a first and second CSU. A pressing pressure of 200 MPa and carbonization temperature of 900° C. yields the compressive strength of 57.6 MPa and 67.5 MPa, which are lower than the compressive strength of CSU for MP:PC=1:2. The MP: PC mass ratio of 1:3 yields comparable density and higher thermal conductivity (e.g., lesser insulation properties) to the MP:PC mass ratio of 1:2.
Table 12 is a summary of the mass and dimensions of the CDER CSUs before and after oxidation and carbonization. Table 13 is a summary of the composition of the CDER CSUs. The CDER CSUs include a 430° C. heat-treated De-CSU having a De:PC mass ratio of 1:2 (De430:PC=1:2); an untreated TI-CSU having a TI:PC mass ratio of 1:2 (TI:PC=1:2); a 430° C. heat-treated TI-CSU having a TI:PC mass ratio of 1:2 (TI430:PC=1:2); an untreated DE-CSU with a De:MP:PC mass ratio of 1:1:4 (De:MP:PC=1:1:4); an untreated TI-CSU having a TI:MP:PC mass ratio of 1:1:4 (TI:MP:PC=1:1:4); a 430° C. heat-treated De-CSU having a De430:MP:PC mass ratio of 1:1:4 (De430:MP:PC=1:1:4); a 450° C. heat-treated De-CSU having a De450:MP:PC mass ratio of 1:1:4 (De450:MP:PC=1:1:4); and a 450° C. heat-treated TI-CSU having a TI450:MP:PC mass ratio of 1:1:4 (De430:MP:PC=1:1:4). After oxidation and carbonization the mass changes due to the evaporation of volatile materials, causing shrinkage in dimensions.
After oxidation and carbonization, the CSUs are tested for the compressive strength and thermal conductivity. The CSUs having De and TI as the only binder (De430:PC, TI430:PC and TI:PC) exhibit compressive strengths lower than 30 MPa. When De and TI are included in the MP to PC ratio of 1:4 in the preparation of CSUs, the compressive strengths exceeds 30 MPa, except for the De430:MP:PC with the compressive strength of 27.73 MPa. The overall carbon content after preparation and before oxidation and carbonization is greater than 70% for all CSUs. The thermal conductivity of CSUs ranges from 0.175 to 0.226 W/m·K, which is significantly lower than that of concrete (1.7 W/m·K). The density ranges from 0.89 to 1.14 g/cm3, supporting the use of CSU as a building material to reduce the self-weight of a structure.
Table 14 is a summary of the mass and dimensions of the P&H treated CDER CSUs. Table 15 is a summary of the composition of P&H treated CDER CSUs. The P&H treated CSUs include a first and a second P&H De-CSU (DEP&H+MP+PC) and a first and second P&H TI-CSU (TIP&H+MP+PC). The CSUs are prepared with P&H-treated De and TI and tested for their compressive strengths. The CSUs have a mixing ratio by weight of CDER:MP:PC=1:1:4 using 100 MPa pressing pressure.
Table 16 is a summary of the mass and dimensions of the increased CDER material content CSUs. Table 17 is a summary of the composition of the increased CDER material content CSUs. The increased CDER material content CSUs include a first and second De-CSU (DE:MP:PC (1.5:1:5)); and a first and second TI-CSU (TI:MP:PC (1.5:1:5)). The CSUs are prepared with increased CDER material content to optimize CDER material content for two different pressing pressures (100 MPa & 200 MPa). These CSUs have a mixing ratio of CDER:MP:PC=1.5:1:5, maintaining a total binder (1.5+1=2.5) to char (5) ratio of 1:2. The thermal conductivity of CSUs ranges from 0.175 to 0.192 W/m·K and the density ranges from 0.98 to 1.08 g/cm3.
A steel mold may be used to fabricate the CSUs. The steel mold has dimensions of about 25 mm×about 25 mm×about 100 mm to form rectangular CSUs. MP (coal) is mixed with PC at a mixing ratio by weight of about MP: PC=1:2 for flexural testing. A ball mill machine is used to grind a large quantity of about 2 kg of PC to obtain particle sizes less than 40 μm (#400 sieve). About 10 mm and about 20 mm stainless steel balls are placed inside a drum during the grinding process. The ball milling is conducted for 24 hours at a speed of 50 rpm in one directional rotation. After grinding, the PC is sieved using a #400 sieve. More than 99% of the PC passed through the sieve. About 300 g of manually ground MP is ball-milled with about 600 g of PC to mix about evenly for about 24 hours at a speed of about 50 rpm to form a CSU mixture. The CSU mixture is oven-dried at a temperature of 150° C. for 24 hours before storing it in an air-tight container.
Table 18 is a summary of the physical properties of the CSU. About 75 grams of the CSU mixture is used to fabricate each CSU with a pressing pressure of about 100 MPa for about 10 minutes. A 50-ton capacity pressing equipment is used to apply the pressure on the CSU mixture. The filling heights from opposite sides are checked before pressing to make sure uniform compression throughout the length of the sample. The mold is placed under the center of the pressing piston to complete the pressing.
The gas connection for the tube furnace was setup for oxidation and carbonization. An oxidation stabilization process is conducted by heating the CSU to about 245° C. in an air environment at a rate of about 0.5° C./min. The CSU is held at temperature for about 12 hours. The CSU is cooled down to room temperature of about 25° C. at a rate of about 2° C./min. A carbonization process is conducted by heating the CSU to about 900° C. under nitrogen flow at a heating rate of about 1° C./min. The temperature is held for about 1 hour and cooled down at a cooling rate of about 2° C./min. The average densities before and after oxidation and carbonization are about 1.11 gm/cm3 and about 1.15 gm/cm3, respectively, which is much lower than a typical concrete density of 2.8 g/cm3.
Table 19 shows the physical properties of the cylindrical CSU samples before oxidation and carbonization. Table 20 shows the physical properties of the cylindrical CSU samples after oxidation and carbonization. Cylindrical CSU samples are fabricated using MP and PC with a mass ratio of 1:2. A steel mold is used under about 100 MPa pressing pressure for 10 minutes. The oxidation stabilization process is conducted by heating the compacted sample to about 245° C. in an air environment at a rate of 0.5° C./min. The mixture is held at temperature for about 12 hours before cooling it down to room temperature of about 25° C. at a rate of about 2° C./min. The carbonization process is conducted by heating the samples to about 900° C. under nitrogen flow at a heating rate of about 1° C./min. The temperature is held for about 1 hour and cooled down at a cooling rate of about 2° C./min. The average density after compression is 1.15 gm/cm3, and the average density after oxidation stabilization and carbonization is 1.17 gm/cm3.
Table 21 shows the physical properties of CSU samples.
The present disclosure provides, among other things, the following embodiments, each of which can be considered as optionally including any alternate embodiment.
Clause 1. A composition, comprising:
Clause 2. The composition of clause 1, wherein the CDER material comprises a tetralin insoluble (TI), a deposit (De), a distillation residue (DR), a residue (Re), or combinations thereof.
Clause 3. The composition of clause 1, wherein the pitch material comprises a mesophase pitch from coal (MP (coal)) a mesophase pitch from naphthalene (MP (naphthalene)), a coal tar pitch, or combinations thereof.
Clause 4. The composition of clause 1, wherein the PC is pyrolyzed between about 600° C. and about 900° C.
Clause 5. The composition of clause 1, wherein the grain size of the PC is about 0.05 mm to about 1.0 mm, such as about 0.25 mm to about 0.5 mm.
Clause 6. The composition of clause 2, wherein the porosity of the PC is about 0.01% to about 0.025%.
Clause 7. The composition of clause 1, wherein the average pore size of the PC is about 1 nm to about 2 nm.
Clause 8. The composition of clause 1, wherein the specific surface area of the PC is about 200 m2/g to about 300 m2/g.
Clause 9. A carbon-based structural unit (CSU), comprising:
Clause 10. The CSU of clause 9, wherein the CDER material comprises a tetralin insoluble (TI), a deposit (De), a distillation residue (DR), a residue (Re), or combinations thereof.
Clause 11. The CSU of clause 9, wherein the pitch material comprises a mesophase pitch from coal (MP (coal)) a mesophase pitch from naphthalene (MP (naphthalene)), a coal tar pitch, or combinations thereof.
Clause 12. The CSU of clause 9, wherein the PC is pyrolyzed between about 600° C. and about 900° C.
Clause 13. The CSU of clause 9, wherein the grain size of the PC is about 0.05 mm to about 1.0 mm, such as about 0.25 mm to about 0.5 mm.
Clause 14. The CSU of clause 13, wherein the porosity of the PC is about 0.01% to about 0.025%.
Clause 15. The CSU of clause 9, wherein the average pore size of the PC is about 1 nm to about 2 nm.
Clause 16. The CSU of clause 9, wherein the specific surface area of the PC is about 200 m2/g to about 300 m2/g.
Clause 17. The CSU of clause 9, wherein the CSU has a compressive strength of about 10 MPa to about 120 MPa.
Clause 18. The CSU of clause 9, wherein the CSU has an average density of the CSUs is from about 0.5 g/cm3 1.5 g/cm3.
Clause 19. The CSU of clause 9, wherein the CSU has a thermal conductivity from about 0.1 W/m·K to about 0.5 W/m·K.
Clause 20. A method of making a composition, comprising:
Clause 21. The method of clause 20, wherein the composition further comprises about 0% to about 99% of a pitch material.
Clause 22. The method of clause 21, wherein the pitch material comprises a mesophase pitch from coal (MP (coal)) a mesophase pitch from naphthalene (MP (naphthalene)), a coal tar pitch, or combinations thereof.
Clause 23. The composition of clause 20, wherein the CDER material comprises a tetralin insoluble (TI), a deposit (De), a distillation residue (DR), a residue (Re), or combinations thereof.
Clause 24. The method of clause 20, wherein the PC is pyrolyzed between about 600° C. and about 900° C.
Clause 25. The method of clause 20, wherein the grain size of the PC is about 0.05 mm to about 1.0 mm, such as about 0.25 mm to about 0.5 mm.
Clause 26. The method of clause 20, wherein the porosity of the PC is about 0.01% to about 0.025%.
Clause 27. The composition of clause 20, wherein the average pore size of the PC is about 1 nm to about 2 nm.
Clause 28. The method of clause 20, wherein the specific surface area of the PC is about 200 m2/g to about 300 m2/g.
Clause 29. The method of clause 20, wherein the milled PC may has a diameter of less than about 35 μm.
Clause 30. The method of clause 20-29, further comprising heat-treating the CDER material to form a heat-treated CDER, wherein the heat-treatment occurs between about 400° C. and 500° C.
Clause 31. The method of clause 20-29, further comprising pressure heat-treating (P&H treating) the CDER material to form a pressure heat-treated (P&H treated) CDER, wherein the P&H treatment occurs between about 400° C. and 500° C. at an applied pressure of about 2 MPa to about 6 MPa.
Clause 32. The method of clause 31, wherein the P&H treatment includes a heating rate is about 2.5° C./min to about 7.5° C./min from room temperature to the P&H treatment temperature.
Clause 33. The method of clause 30-32, further comprising molding the composition to form a CSU.
Clause 34. The method of clause 33, wherein the composition is molded into the CSU under an applied pressure of about 50 MPa to about 500 MPa.
Clause 35. The method of clause 34, further comprising oxidizing the CSU through an oxidation process and carbonizing the CSU through a carbonization process.
Clause 36. The method of clause 35, wherein the oxidation process comprises:
Clause 37. The method of clause 35 and 36, wherein the carbonization process comprises:
As is apparent from the foregoing general description and the specific aspects, while forms of the aspects have been illustrated and described, various modifications can be made without departing from the spirit and scope of the present disclosure. Accordingly, it is not intended that the present disclosure be limited thereby. Likewise, the term “comprising” is considered synonymous with the term “including.” Likewise whenever a composition, process operation, process operations, an element or a group of elements is preceded with the transitional phrase “comprising,” it is understood that we also contemplate the same composition or group of elements with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “Is” preceding the recitation of the composition, process operation, process operations, element, or elements and vice versa, such as the terms “comprising,” “consisting essentially of,” “consisting of” also include the product of the combinations of elements listed after the term.
For purposes of this present disclosure, and unless otherwise specified, all numerical values within the detailed description and the claims herein are modified by “about” or “approximately” the indicated value, and consider experimental error and variations that would be expected by a person having ordinary skill in the art. For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. For example, the recitation of the numerical range 1 to 5 includes the subranges 1 to 4, 1.5 to 4.5, 1 to 2, among other subranges. As another example, the recitation of the numerical ranges 1 to 5, such as 2 to 4, includes the subranges 1 to 4 and 2 to 5, among other subranges. Additionally, within a range includes every point or individual value between its end points even though not explicitly recited. For example, the recitation of the numerical range 1 to 5 includes the numbers 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, among other numbers. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.
While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof.
This application claims was made with government support under DE-FE0031996 awarded by the Department of Energy. The government has certain rights in the invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2023/026120 | 6/23/2023 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63355426 | Jun 2022 | US |
