Carbon Gasification Efficiency Research Articles

Exploring Biomass Conversion Technologies: From Raw Materials to Valuable Products

The global demand for eco-friendly energy has propelled biomass into the spotlight. This report delves into biomass conversion technologies, including biochemical and thermochemical processes, with a focus on hydrothermal conversion. It highlights challenges related to cost-effectiveness and commercial viability. Thermochemical conversion processes, such as pyrolysis and combustion, unlock energy from organic matter. Hydrothermal processing's three approaches and their efficiency are discussed, particularly in biofuels, chemicals, and biochar production. The review analyzes hydrothermal gasification, emphasizing its efficiency and minimal processing time. Carbon and hydrogen gasification efficiencies are crucial in determining gas yields in supercritical conditions. Yield distribution and the influence of feedstock nature and composition on product yield are examined. In conclusion, this report offers insights into biomass conversion technologies and their sustainability for energy and chemical needs.

Supercritical water synthesized Ni/ZrO2 catalyst and its application in the harmless treatment of oilfield wastewater in supercritical water

Supercritical water (SCW) catalytic gasification is a clean and efficient technology with prominent advantages in treating oily wastewater generated in oilfields. SCW synthesis is a promising one-step preparation method for nano-catalytic materials, while the influence of organic matter on SCW synthesis materials remains to be studied. This study focuses on the synthesis of the Ni/ZrO2 catalysts by the supercritical water synthesis (SCWS) method, particularly examining how different types and concentrations of organic matter affect the catalysts’ pore information and structural characteristics. It found that glycerol acted as a more effective precursor for generating reducing gases compared to glucose. This is attributed to glycerol’s capacity in SCW to generate reducing gases for activating a greater number of Ni site within the catalyst, and the 5 wt% glycerol should be a proper concentration for SCWS of Ni/ZrO2. When employed in SCW treatment of oilfield wastewater, the Ni/ZrO2 catalyst demonstrated impressive results, achieving the carbon gasification efficiency of 99.1 % and a chemical oxygen demand (COD) removal efficiency of 100 % at 500°C. These findings indicate that the SCW technique can effectively and harmlessly treat oilfield wastewater using the Ni/ZrO2 catalyst under relatively mild conditions, showing its potential as an innovative solution for wastewater management in the oil industry.

Study of potassium deactivation rule in supercritical water gasification of coal with K2CO3 as catalyst

K2CO3 has a good catalytic effect in supercritical water gasification (SCWG) of coal. However, researchers have mainly focused on the effects of coal gasification, while the potassium mass transfer process has rarely been studied. Herein, the distribution pattern of potassium during the SCWG of coal and the factors influencing potassium deactivation were experimentally obtained. Through the detection and analysis of the residues after the SCWG of coal, it is found that potassium only exists in the forms of liquid and solid and the potassium in the residue exists in the form of insoluble potassium silica alumina, which does not have a catalytic effect. At a high reaction temperature, the reaction time is longer, and when the silica–aluminum content in coal is higher, the potassium deactivate rate is also higher. The molar contents of potassium and aluminum in the coal gasification residue are linearly correlated, with a ratio of approximately 1:1. Reducing the aluminum content in coal can effectively reduce potassium deactivation. In the SCWG of the Hebi coal, the deactivation rate of potassium reduced from 80.88 % to 17.75 % after acid washing. In the SCWG of the ash-free coal, the carbon gasification efficiency (CE) and potassium content in the liquid were above 95 % after each experiment, there was no deactivation of potassium, and the residual potassium solution remained catalytically effective after the SCWG of the ash-free coal.

Experiment and simulation assessment of supercritical underground coal gasification in deep coal seam

To explain the impact of geological and process factors on underground coal gasification in deep coal seam (>2200 m) and promote the efficient and clean extraction and conversion of coal, this study employs the orthogonal experimental design method to investigate the impact of CO2 coefficient (0–1), moisture content (30–80 wt%), calcite content (0–10 wt%), albite content (0–10 wt%), kaolinite content (0–20 wt%), reaction temperature (550–650 °C), and reaction pressure (23–27 MPa) on the characteristics of coal underground gasification under supercritical H2O/CO2 conditions. Furthermore, range analysis and variance analysis are utilized to determine the degree of influence of each factor and the interaction between factors. Finally, the Gibbs free energy minimization method is used to conduct a thermodynamic equilibrium analysis of coal supercritical H2O/CO2 gasification at high temperatures (750–1000 °C). The results indicate that the three most significant factors affecting the process of coal supercritical H2O/CO2 gasification are the CO2 coefficient, moisture content, and reaction temperature. The maximum carbon gasification efficiency at 650 °C in experimental cases and 1000 °C in simulation cases is 22.2% and 88.1%, respectively. Although the addition of CO2 at lower temperatures reduces the carbon gasification efficiency, at high temperatures (>900 °C), a higher initial CO2 concentration increases the carbon gasification efficiency. The addition of CO2 under conditions of low moisture content increases the mole fraction of H2, but reduces it under conditions of high moisture content (≥70 wt%). Among the three minerals, calcite has the most significant influence on the gasification process.

Fabrication and catalytic assessment of Ni/Ce–Zr–O catalyst for enhanced hydrogen production via steam reforming of glycerol

The valorization of glycerol, a plentiful byproduct derived from the biodiesel industry, for green hydrogen production via steam reforming (GSR) has attracted considerable attention. Nevertheless, catalysts developed for GSR encounter critical obstacles related to thermal stability and coke deposition during prolonged operations. In this study, we strategically employed thermally stable ZrO2 as a support along with redox-active Ce as a promoter for Ni to optimize both the preparation method and constituent content of the Ce-promoted Ni/ZrO2 catalyst for GSR. The physicochemical properties of both fresh and GSR-used catalysts were investigated using a range of characterization techniques, including XRD, H2-TPR, SEM-EDS/TEM, N2 adsorption/desorption, and TGA. The results demonstrate that the sol-gel method yields a Ni/Ce–Zr–O catalyst with smaller Ni crystals and a higher surface nickel content compared to the step impregnation and co-precipitation methods, thereby achieving enhanced catalytic activity. Moreover, the catalyst prepared by the sol-gel method exhibited excellent activity stability at elevated feedstock concentrations. Furthermore, it has been determined that there is an optimized amount of Ce doping for the Ni/ZrO2 catalyst, which allows the catalyst to achieve the highest pore parameters and surface nickel content. Among the studied catalysts, the one containing 30/50 wt% of designed CeO2/ZrO2 achieved the highest and most stable H2 yield (4.32 mol⋅mol−1) and carbon gasification efficiency (70.28 %) during a 24-h's GSR with a feedstock concentration of 15 wt% at 500 °C (with a WHSV of 45 h−1). Importantly, this optimized Ni/Ce–Zr–O catalyst effectively eliminates the deposition of filamentous/crystallized coke during long-term GSR operation due to enhanced oxygen vacancies created by the formed CexZr1-xO2 species, making it highly promising for large-scale applications.

Thermochemical conversion of guaiacol with supercritical CO2: Experimental insights

The excessive CO2 in the environment resulting from the combustion of fossil fuels has posed a significant challenge in terms of its conversion and utilization. In this work, the thermochemical conversion of guaiacol under supercritical CO2 (scCO2) was proposed, which not only enabled the consumption of CO2 but also facilitated the conversion of biomass into valuable products. It was concluded that the carbon gasification efficiency (CE) and hydrogen gasification efficiency (HE) were 37.10 % and 51.77 %, respectively, when the CO reached the maximum of 8.72 ± 0.28 mol/kg at 700 °C for 20 min. The addition of catalyst promoted the production of H2 and increased CE, the H2 yield of guaiacol gasification under different catalysts was ordered as Al2O3 > KOH > without catalyst > KCl. As the reaction temperature increased, the unreacted guaiacol and phenol decreased and were gradually converted to liquid products such as pyrene and benzo[c]phenanthrene. With the increase in reaction temperature, the more fully guaiacol was reacted, the easier it was to carbonize and form more carbon microspheres. In addition, reaction pathways for free radicals were proposed, including cleavage of free radicals, isomerization of free radicals, secondary cleavage of free radicals and recombination of free radicals. In short, degrading guaiacol using scCO2 is a feasible approach, which provides a new direction for the disposal and energy recovery of biomass in the future.

Experimental study of diphenylmethane gasification with supercritical CO2

Supercritical carbon dioxide (SCCO2) gasification reaction is one of the current popular research fields with wide application prospects in green chemical synthesis, environmental protection and energy conversion. This work aimed to investigate the effects of different conditions on the gas–liquid-solid three-phase products during the reaction of SCCO2 gasification of diphenylmethane. As a result, the carbon gasification efficiency (CE) and the hydrogen gasification efficiency (HE) were 25.99 % and 21.97 % respectively at 700 ℃ for 40 min, in which the CO reached the maximum of 15.64 ± 0.16 mol/kg. As the temperature and residence time increased, the apparent morphology of solid products became more homogeneous. In addition, based on the theories of cleavage of free radicals, secondary cleavage of free radicals and binding of free radicals, three pathways for the generation of fluorene, biphenyl and m-terphenyl were postulated. The experimental results provide fundamental data and theoretical support for an in-depth understanding of the reactions mechanism under the SCCO2 atmosphere, which is of great significance for deepening our knowledge of supercritical carbon dioxide reduction reactions and promoting green chemical synthesis research.

Screening of ten different plants in the process of supercritical water gasification

It is important to know the limitations of the supercritical water gasification (SCWG) in terms of behavior of different biomasses, especially when determining whether SCWG is a suitable conversion process for a certain biomass. Ten different biomasses (eight different plant species, of which two were grown in two different sites) were processed to evaluate this aspect. Moist and dry, woody and grassy biomasses were gasified in the same experimental setup under similar conditions. Only small differences could be seen in the gasification experiments. The carbon gasification efficiency was 60.3 ± 5.1 %, the gas compositions were very similar. Solid deposits formed in all experiments in the same temperature zone of the reactor containing coke, salt building elements and heavy metals, sometimes leading to plugging. Nevertheless, an experimental duration of 6 h could be achieved for the dry biomasses. The experiment with the moist biomass Reed Canary Grass was ended early due to plugging of the feed tubing which is due to the different size reduction procedure for moist biomasses resulting in bigger biomass particles. This emphasizes the importance of sufficient size reduction prior to the experiment. Potassium addition as a homogeneous catalyst, in form of potassium hydroxide, has proven to be beneficial regarding gasification efficiency, but poses a threat regarding plugging due to salt deposits in the system.

Optimization of coal chemical process parameters and energy saving and emission reduction based on genetic algorithm

Abstract Coal is an important energy resource. How to utilize it efficiently and cleanly is a hot topic nowadays. In the coal gasification process, the process parameter indexes have a significant impact, and the uncertainty of these factors will lead to a decrease in the quality of gas production. Therefore, in this paper, the uncertainty of process parameters is considered, and Aspen plus software with the Monte Carlo method is used to simulate the coal chemical process and measure the effect of uncertainty of process parameters on the yield of the coal gasification process. On this basis, in addition, coal flow rate, pressure, and steam/oxygen are taken as the process parameters and optimized, and three sets of multi-objective optimization models are established with gas calorific value, gasification efficiency, and gas yield, respectively, which are solved by improved multi-objective genetic algorithm based on crossover operator and variational operator to obtain Pareto curves, so as to adjust the parameter values according to the actual needs. The results show that the fluctuation of pressure has a big influence on the carbon conversion rate and gasification efficiency, and the carbon conversion rate and gasification efficiency can be made more stable by controlling the change of pressure. The improved genetic algorithm NSGA-II can reach the actual optimal objective function value in both high and low iteration times, providing the required parameters for the decision maker, and the optimal program results in TEC of 402,758 kW and CO2 content of 0.12%, which is effective in energy saving and emission reduction.

Production of green hydrogen from sewage sludge / algae in agriculture diesel engine: Performance Evaluation

Alternative fuel opportunities can satisfy energy security and reduce carbon emissions. In this regard, the hydrogen fuel is derived from the source of environmental pollutants like sewage and algae wastewater through hydrothermal gasification technique using a KOH catalyst with varied gasification process parameters of duration and temperature of 6–30 min and 500-800 °C. The novelty of the work is to identify the optimum gasification process parameter for obtaining the maximum hydrogen yield using a KOH catalyst as an alternative fuel for agricultural engine applications. Influences of gasification processing time and temperature on H2 selectivity, Carbon gasification efficiency (CE), Lower heating value (LHV), Hydrogen yield potential (HYP), and gasification efficiency (GE) were studied. Its results showed that the gasifier operated at 800 °C for 30 min, offering maximum hydrogen yield (26 mol/kg) and gasification efficiency (58 %). The synthesized H2 was an alternative fuel blended with diesel fuel/TiO2 nanoparticles. It was experimentally studied using an internal combustion engine. Influences of H2 on engine performance, like brake-specific fuel consumption, brake thermal efficiency and emission performances, were measured and compared with diesel fuel. The results showed that DH20T has the least (420g/kWh) brake-specific fuel consumption (BSFC) and superior brake thermal efficiency of about 25.2 %. The emission results revealed that the DH20T blend showed the NOX value increased by almost 10.97 % compared to diesel fuel, whereas the CO, UHC, and smoke values reduced by roughly 31.25, 28.34, and 42.35 %. The optimum fuel blend (DH20T) result is recommended for agricultural engine applications.

Municipal solid waste air gasification using waste marble powder as a catalyst for syngas production

Waste marble powder (WMP), the main pollutant in the marble processing industry, is predominantly composed of calcite. Its rich calcium-based nature, derived from calcite, positions it as an excellent source for a CO2 sorbent, making it highly conducive to serving as a catalyst. Also, extraction of energy from MSW is the best option to discard solid waste along with protection from global warming and landfill burden. The present study aims to investigate MSW potential as feedstock with WMP as a CO2 sorbent for syngas in air gasification lab-scale fixed-bed gasifier. The system was initially tested on different equivalence ratios (ER) (0.25, 0.30, and 0.35) to search for an optimum value. The optimum value of ER for this study was found to be 0.30 with the composition of CO, CO2, CH4, and H2 were 10, 8.97, 1.67, and 6.65 vol%, respectively. The main study investigated the influence of different weight ratios of WMP to MSW (0.05, 0.1, 0.15, and 0.2) on the gas composition, carbon conversion efficiency, and carbon gasification efficiency, and higher heating values. The results indicated that the presence of WMP promotes H2 and CO significantly, whereas CO2 content was reduced to 0.20 vol% when compared to runs without utilizing WMP (9 vol%). For this study, loading the WMP catalyst exhibits a remarkable effect on syngas composition with the optimum ratio of 0.1–0.15.

Catalytic gasification of anthracene in supercritical water with Ni/TiO2 catalyst: Products distribution and kinetics

Supercritical water gasification (SCWG) is a clean and efficient utilization way of coal to produce hydrogen-rich gas. As the consumption of PAHs is the rate-determining step to the rapid gasification of coal in SCW, anthracene was used as the simplest model of PAHs to investigate the ring-opening and gasification mechanism of PAH compounds in supercritical water (SCW). The SCWG experiments of 7.5 wt% anthracene were carried out in SCW under various temperatures (400–550 °C) and residence times (5–30 min). Ni/TiO2 catalysts were added to achieve the fast and complete gasification of anthracene, and a carbon gasification efficiency of 95.73% was achieved at 500 °C, which was 100 times higher than 0.95% of the non-catalytic condition. A kinetic model including a detailed reaction pathway for anthracene was successfully proposed to reveal the catalytic mechanism of anthracene gasification in SCW. The results indicated that the addition of Ni/TiO2 effectively reduced the activation energy of anthracene hydrogenation to generate CH4, and this reaction was most critical for the generation of CH4. This work guided the determination of key parameters for industrial-scale reactors to achieve an optimal design, providing a promising method for in-situ elimination of char during SCWG of coal.

Hydrogen production by kraft black liquor supercritical water gasification: Reaction pathway and kinetic

Kraft black liquor (KBL) supercritical water gasification (SCWG) has significant implications for carbon emission reduction and energy efficiency improvement in the pulp industry. This research focuses on investigating the SCWG of KBL under different reaction conditions, including reaction times (5–30 min), temperatures (450–650 °C), and feed concentrations (5%–20%), utilizing a high heating rate batch reactor. The performance of the gasification process is evaluated by analyzing gaseous, liquid, and solid products. Remarkable achievements in carbon gasification efficiency (CGE) of 95.28% and COD removal of 99.90% are attained at 650 °C, 30 min, and 10 wt% feed concentration. The liquid-phase products primarily comprise aromatic compounds, particularly phenolics, with the possible presence of reactive nonaromatic compounds such as cyclopentanone. Lower temperatures favor the formation of solid products, which result from phenolic agglomeration reactions leading to char formation. The research also explores the SCWG reaction pathway of KBL and develops a comprehensive twelve-lumped quantitative kinetic model. This work provides valuable engineering parameters for reactor design, optimization, and numerical simulations, facilitating advancements in SCWG of KBL technology.

Experimental investigation on the supercritical water gasification of coal by integrating the hydrogen oxidation process into a supercritical water fluidized bed

The autothermal gasification process is crucial for the industrial application of supercritical water gasification (SCWG) in a supercritical water (SCW) fluidized bed. However, researchers often consider providing external heat to investigate the gasification process and seldom achieve autothermal gasification. Herein, the hydrogen oxidation process was integrated into an SCW fluidized bed to provide heat for the gasification process and to investigate gasification results under various experimental conditions. Using this method, a carbon gasification efficiency of 98.6% and a H2 yield of 68.03 mol/kg were obtained at an experimental temperature of 690 °C. After the gasification products were partially oxidized in the oxidation zone, a H2 yield of 13.6 mol/kg and a total carbon content of <10 ppm in the liquid products were obtained. Compared with the uniform electrical heating method, the heating method based on the hydrogen oxidation process in SCW has obvious advantages, can improve the coal slurry concentration and mass ratio of coal to SCW in the reactor, and maintain a milder temperature under near-complete gasification conditions. This work provides a basis for heat supply in the industrial application of SCWG technology.

Hydrothermal gasification of glucose for H2 production using Ni–Al2O3 nanocatalyst

Hydrothermal gasification is a promising technology for converting biomass into syngas (H2/CO). A substantial challenge of hydrothermal gasification for producing hydrogen is the unwanted deposition of graphitic coke and metal particle agglomeration on the catalyst active sites. In this contribution, we hypothesize and examine controlling the active site nickel nanoparticle size (2, 9, 23 and 32 nm) through synthesis on supported mesoporous alumina (Al2O3). Nanoparticles were synthesized from nickel acetylacetonate (Ni(acac)2) by varying the molar ratio of oleylamine (OA) to trioctylphosphine (TOP) which gave controlled sizes of nanoparticles. Based on catalyst analysis, the 11 wt% Ni–Al2O3 containing 2 nm Ni was further evaluated for hydrothermal gasification of glucose for the production of syngas (H2/CO) at 500 °C temperature and 30 min reaction time. This nanocatalyst was found to significantly increase H2 yield compared to a previously prepared impregnated catalyst having larger Ni active sites. Graphitic coke deposition was minimized while the total organic carbon destruction (TOC) and carbon gasification efficiency (CGE) were both enhanced with the nanocatalyst. Almost double the yield of H2 (1.94 times higher) was achieved compared to the impregnated catalyst. This is attributed to the larger surface area, higher percentage of metal dispersion and uniform size distribution of active metal nanoparticles on the support.

Enhanced oxygen activity of LaFeO3 oxygen carriers in biomass chemical looping gasification coupled with CO2/H2O splitting by fragmented flaky structure

Considering that the conventional modification of metal doping may bring excessive cost escalation and more pollution, for the sol–gel method, a more cost-effective and eco-friendly modification method was proposed to enhance the oxygen activity of LaFeO3 and its doped oxygen carriers (OCs). In this work, LaFeO3 OCs with fragmented flaky structure was prepared by modification of adjusting the sol to weak alkalinity with ammonia and adding the complexing agent ethylene glycol. Then, it was applied in Biomass chemical looping gasification (BCLG) coupled with CO2/H2O splitting to produce high-quality syngas and achieve cascade conversion of carbon in biomass, and its performance and reaction mechanism were investigated by fixed bed test. The results showed that the fragmented flaky structure endowed the LaFeO3 OCs with more robust oxygen activity, thus realizing efficient lattice oxygen migration which increased the gas yield of BCLG stage from 695.6 mL/g to 851.2 mL/g at 900 °C, and the carbon conversion and gasification efficiency reached 65.6% and 64.4%, respectively. Despite the predominant role of residual char in the gas generation of splitting stage, the reduced OCs still possesses exceptional CO2 and H2O splitting ability. Among them, CO2 splitting was mainly carried out by the activation of Fe0 and alkaline active sites from the reduced OCs, while H2O splitting depended more on the decomposition of H2O molecules by oxygen vacancies. Moreover, this OCs exhibited outstanding stability in 10 cycles, and the total gas yield in two stages was consistently maintained around 1030.1 mL/g and 1069.6 mL/g, respectively. This work found that the LaFeO3 OCs with fragmented flaky structure is a prospective material for chemical looping technology.

A novel biotar-derived porous carbon supported Ru catalyst for hydrogen production from supercritical water gasification of glycerol

A novel Ru/BPC catalysts were prepared by impregnating Ru metal into porous carbon derived from waste bio-tar as a carrier matrix activated by KOH. The results of the catalytic supercritical water gasification (SCWG) of glycerol showed a carbon gasification efficiency (CGE) of 64.1% and a H2 yield of 20.9 mmol·g−1at 425 °C and 25 MPa for 20 min due to the synergistic effect of Ru and active alkali metals present in the Ru/BPC material. In the catalyst cycling experiments, the exposure of the active site in the catalyst further increased the catalytic activity, the H2 yield increased from 21.0 mmol g−1 to 40.8 mmol g−1 with 82.1% CGE. Catalyst characterization indicates that the rich pore structure and the number of unsaturated carbon atoms of BPC enhanced the adsorption of Ru metal. This study provides new ideas for waste biomass resource utilization and cheap catalyst preparation for hydrothermal gasification process.

Experimental study on supercritical water gasification of oily sludge using a continuous two-step method

Supercritical water gasification (SCWG) technology can convert oily sludge into hydrogen-rich gas. To achieve high gasification efficiency of oily sludge with a high oil concentration under mild conditions, a two-step method involving a desorption process and a catalytic gasification process using Raney-Ni catalyst was investigated. High oil removal efficiency (99.57%) and carbon gasification efficiency (93.87%) were achieved. The lowest wastewater total organic carbon, oil content, and carbon content in the solid residues were 4.88 ppm, 0.08% and 0.88%, respectively, using a gasification temperature of 600 °C, treatment concentration of 1.11 wt%, gasification time of 70.7 s, and the optimal desorption temperature of 390 °C. The main organic carbon component in the solid residues was cellulose, which is environmentally safe. As the treatment concentration increased, the two-step method outperformed the single-step method. The mechanism for the two-step SCWG of oily sludge was revealed. In the first step, supercritical water is used in the desorption unit to achieve a high oil removal efficiency with few liquid products generated. In the second step, the Raney-Ni catalyst promotes efficient gasification of high-concentration oil at a low temperature. This research provides valuable insights into the effective SCWG of oily sludge at a low temperature.

Clean treatment and resource utilization of oilfield wastewater using supercritical water gasification

Unconventional oil and gas resources are expected to be recovered efficiently by multi-component supercritical thermal fluid (MCSCTF) which is generated based on supercritical water gasification (SCWG) of oilfield wastewater and hydrogen oxidation technology. In this paper, SCWG experiments of oilfield wastewater were performed under 550–750 °C, 2–15 min, 21–29 MPa, and feedstock concentration of 2–10 wt%. High temperatures, extended residence times, and low concentrations encouraged the production of gases. There was no significant change in SCWG as the pressure changed. The highest H2 yields and carbon gasification efficiency (CE) were 52.31 mol/kg and 97.59%, respectively. The SCWG mechanism was summarized to describe the conversion details. The SCWG of oilfield wastewater has the fastest initial rate to present a trend of deceleration and the activation energy of CE was calculated as 135.7 kJ/mol. The reason for gasification deceleration was explained by the proposed gaseous product kinetics. Small molecules and saturated hydrocarbons etc. (Int 1) can be quickly decomposed while the decomposition of phenols and aromatic hydrocarbons etc. (Int 2) is slower. Inhibition of Int 2 generation and enhanced Int 2 decomposition is the key to total gasification. This work is useful for reactor design and process intensification.

K2CO3-catalyzed gasification of coal of different ranks in supercritical water for hydrogen production: A general kinetic model with good coal adaptability

Supercritical water gasification (SCWG) of coal provides a new solution for the green transformation and upgrading of traditional coal industry. Considering the good coal adaptability of SCWG and the excellent catalytic performance of K2CO3, a new kinetic model was developed in this work for predicting the catalytic gasification characteristics of coal of different ranks in supercritical water (SCW). In this model, various ranks of coal are characterized by the combination of three types of primary coal in different proportions, and the proportions can be obtained based on elemental analysis data and matrix computation. The SCWG of various ranks of coal can be considered as a combination of reactions of three types of primary coal in SCW. The model contains a total of 18 reactions, and various intermediates are represented by phenol and a high-carbon hydrocarbon. K2CO3-catalyzed SCWG experimental data of three different coal samples obtained in an improved quartz tube reactor system were used for the determination of model kinetic parameters. Then the experimental results of catalytic SCWG of other coal samples were used for the model validation, and it was found that the model can effectively predict the variations of gaseous products within an acceptable error. Afterward, the model was used to predict carbon gasification efficiency and gas compositions for coal of different ranks and to analyze carbon distribution and reaction rates for specific coal. The proposed kinetic model fits well with the good coal adaptability of SCWG technology, and it has great significance for the promotion of SCWG technology.