Catalytic Steam Gasification Research Articles

Waste furniture gasification using rice husk based char catalysts for enhanced hydrogen generation

Present study provides biohydrogen production methods from waste furniture via catalytic steam gasification with bio-char catalysts (raw char, KOH-activated char and steam-activated char). Total gas yield for the prepared chars was in the order of KOH-activated char > steam-activated char > raw char, whereas, H2 selectivity was in the sequence of raw char > steam-activated char > KOH-activated char. Though KOH-activated char showed the highest gas yield, highest H2 selectivity was obtained at the gasification experiment with raw char due to the large amount of Ca and K and its reasonable surface area (146.89 m2/g). Although the activation of raw biochar results in the increase of gas yield, it has the negative effect on H2 generation due to the removal of alkali and alkaline earth metals for the KOH activated char and steam-activated char. This study shows that raw bio-char could be a potential solution for eco-friendly hydrogen production.

Chemical looping catalytic steam gasification (CLCSG) of algae over La1-xBaxFeO3 perovskites for syngas production

Multifunctional perovskite-type oxides (ABO3) with flexible chemical tailoring characteristics and unique physical properties, are attracting an ever-increasing attention of scientists in the field of biomass chemical looping gasification process. Barium substituted lanthanum ferrite La1-xBaxFeO3 (x = 0, 0.3, 0.5, 0.7, 0.9, 1.0) with perovskite structure was used as oxygen carrier for algae chemical looping catalytic steam gasification (CLCSG) process for the first time. The effects of the Ba-substitution, mass ratio of perovskite and algae (P/A), temperature and water injection rate on the gasification performance were investigated. Results showed that the activity of LaFeO3 was dramatically improved by Ba substitution due to the formation of Fe4+/Fe3+ and oxygen vacancies. Among all the doped LaFeO3 perovskites, La0.3Ba0.7FeO3 (L3B7F) exhibited the best performance and gave highest syngas yield, carbon conversion and gasification efficiency. A maximum syngas yield of 1.00 m3/kg-Algae, carbon conversion of 98.86% and gasification efficiency of 96.71% were obtained at 900 °C with a water injection rate of 0.3 ml/min. Continuous high syngas yield and carbon conversion were observed during the cyclic redox tests.

Thermogravimetry of the Steam Gasification of Calluna vulgaris: Kinetic Study

On account of the continuous decrease in oil reserves, as well as the promotion of sustainable policies, there is an increasing interest in biomass conversion processes, which imply the search for new raw materials as energy sources, like forestry and agricultural wastes. On the other hand, gasification seems to be a suitable thermal conversion process for this purpose. This work studied the thermogravimetry of the steam gasification of charcoal from heather (Calluna vulgaris) in order to determine the kinetics of the process under controlled reaction conditions. The variables studied were temperature (from 750 to 900 °C), steam partial pressure (from 0.26 to 0.82 atm), initial charcoal mass (from 50 to 106 mg), particle size (from 0.4 to 2.0 mm), N2 and steam volumetric flows (from 142 to 446 mL·min−1) and catalyst (K2CO3) concentration (from 0 to 10% w/w). The use of the shrinking core model and uniform conversion model allowed us to determine the kinetic parameters of the process. As a result, a positive influence of catalyst concentration was found up to 7.5% w/w. The kinetic study of the catalytic steam gasification showed activation energies of 99.5 and 114.8 kJ·mol−1 and order of reactions (for steam) of 1/2 and 2/3.

Catalytic steam gasification of food waste using Ni-loaded rice husk derived biochar for hydrogen production

The disposal of food waste (FW) is a major cause of environmental contamination. This study reports an environmentally friendly FW disposal method in the form of catalytic steam gasification using various types of Ni-loaded chars (untreated char, steam-treated char, and ZnCl2-treated char). The results were also compared with the gasification results from the Ni catalysts supported on commercial α-alumina (Ni/α-Al2O3). The Ni/steam-treated char showed the maximum hydrogen generation (0.471 mol/(g feedstock•g cat)) because of the high reducibility, high nickel dispersion, large amount of inherent K and Ca, and moderate surface area. The overall gas and H2 yield were observed in the following order: Ni/steam-treated char > Ni/ZnCl2 treated char > Ni/untreated char > Ni/α-Al2O3. Brunauer-Emmett-Teller analysis of various catalysts showed that the treated chars have a mesoporous structure, and the X-ray diffraction, X-ray fluorescence spectroscopy, scanning electron microscopy – energy dispersive spectroscopy showed that the presence of silica in the chars providing the stable support for the Ni loading and prevented coke formation. The chars obtained from biomass pretreatment could be a potential solution for preventing coke formation at high temperatures, thereby increasing the gas yield and enhancing hydrogen generation.

Syngas Production from Two-Stage Sorption-Enhanced Steam Gasification of Sewage Sludge over Bifunctional Ni-Ca Catalyst

To further enhance the syngas production, the bifunctional Ni-CaO/Al2O3 catalyst was introduced into the two-stage sorption-enhanced catalytic steam gasification of sewage sludge (SS) in this study...

Biohydrogen synthesis from catalytic steam gasification of furniture waste using nickel catalysts supported on modified CeO2

Present study evaluated the catalytic steam gasification of furniture waste to enhance the biohydrogen production. To do this, 10 wt% nickel loaded catalysts on the variety of supports (Al2O3, CeO2, CeO2-La2O3, and CeO2–ZrO2) were prepared by the novel solvent deficient method. The hydrogen selectivity (vol%) order of the catalysts was achieved as Ni/CeO2–ZrO2>Ni/CeO2>Ni/Al2O3≃Ni/CeO2-La2O3. The best catalytic activity of Ni/CeO2–ZrO2 catalyst (~82 vol % H2 at 800 °C) was ascribed to the smaller size of nickel crystals, finely dispersed Ni on the catalyst surface, and Ce1-xZrxO2-δ solid solution. The role of Ce1-xZrxO2-δ solid solution in Ni/CeO2–ZrO2 catalyst was observed as bi-functional; acceleration of water-gas-shift and oxidation of carbon reaction. The high resistance of Ni/CeO2–ZrO2 towards the coke formation showed its potential to establish a cost-effective commercial-scale biomass steam gasification process. This study is expected to provide a promising solution for the disposal of furniture wastes for production of clean energy (biohydrogen).

Chemical Looping Catalytic Steam Gasification (CLCSG) of Algae Over La <sub>1-X</sub>Ba <sub>x</sub>FeO <sub>3</sub> Perovskites for Syngas Production

Multifunctional perovskite-type oxides (ABO3) with flexible chemical tailoring characteristics and unique physical properties, are attracting an ever-increasing attention of scientists in the field of biomass chemical looping gasification process. Barium substituted lanthanum ferrite La1-xBaxFeO3 (x=0, 0.3, 0.5, 0.7, 0.9, 1.0) with perovskite structure was used as oxygen carrier for algae chemical looping catalytic steam gasification (CLCSG) process for the first time. The effects of the Ba-substitution, mass ratio of perovskite and algae (P/A), temperature and water injection rate on the gasification performance were investigated. Results showed that the activity of LaFeO3 was dramatically improved by Ba substitution due to the formation of Fe4+/Fe3+ and oxygen vacancies. Among all the doped LaFeO3 perovskites, La0.3Ba0.7FeO3 (L3B7F) exhibited the best performance and gave highest syngas yield, carbon conversion and gasification efficiency. A maximum syngas yield of 1.00 m3/kg‧Algae, carbon conversion of 98.86% and gasification efficiency of 96.71% were obtained at 900 oC with a water injection rate of 0.3 ml/min. Continuous high syngas yield and carbon conversion were observed during the cyclic redox tests.

Integrated adsorption steam gasification for enhanced hydrogen production from palm waste at bench scale plant

The generation of hydrogen-enriched synthesis gas from catalytic steam gasification of biomass with in-situ CO2 capture utilizing CaO has a high perspective as clean energy fuels. The present study focused on the process modeling of catalytic steam gasification of biomass using palm empty fruit bunch (EFB) as biomass for hydrogen generation through experimental work. Experiment work has been carried out using a fluidized bed gasifier on a bench-scale plant. The established model integrates the kinetics of EFB catalytic steam gasification reactions, in-situ capturing of CO2, mass and energy balance calculations. Chemical reaction constants have been calculated via the parameters fitting optimization approach. The influence of operating parameters, mainly temperature, steam to biomass, and sorbent to biomass ratio, was investigated for the hydrogen purity and yield through the experimental study and developed model. The results predicted approximately 75 vol% of the hydrogen purity in the product gas composition. The maximum H2 yield produced from the gasifier was 127 gH2/kg of EFB via experimental setup. The increase in both steam to biomass ratio and temperature enhanced the production of hydrogen gas. Comparing the results with already published literature showed that the current system enables to produce a high amount of hydrogen from EFB.

Py-FTIR-GC/MS Analysis of Volatile Products of Automobile Shredder Residue Pyrolysis.

Automobile shredder residue (ASR) pyrolysis produces solid, liquid, and gaseous products, particularly pyrolysis oil and gas, which could be used as renewable alternative energy resources. Due to the primary pyrolysis reaction not being complete, the yield of gaseous product is low. The pyrolysis tar comprises chemically unstable volatiles before condensing into liquid. Understanding the characteristics of volatile products will aid the design and improvement of subsequent processes. In order to accurately analyze the chemical characteristics and yields of volatile products of ASR primary pyrolysis, TG–FTIR–GC/MS analysis technology was used. According to the analysis results of the Gram–Schmidt profiles, the 3D stack plots, and GC/MS chromatograms of MixASR, ASR, and its main components, the major pyrolytic products of ASR included alkanes, olefins, and alcohols, and both had dense and indistinguishable weak peaks in the wavenumber range of 1900–1400 cm−1. Many of these products have unstable or weaker chemical bonds, such as =CH–, =CH2, –C=C–, and –C=CH2. Hence, more syngas with higher heating values can be obtained with further catalytic pyrolysis gasification, steam gasification, or higher temperature pyrolysis.

Hydrogen-rich energy recovery from microalgae (lipid-extracted) via steam catalytic gasification

Identifying and tackling indispensable developments in microalgae-based bio-economy should be a priority to unravel the contentious water-food-energy-environment nexus that algae inhabit. This research investigated the catalytic and non-catalytic steam gasification of two types of lipid-extracted microalgae biomasses, Chlorella vulgaris and Spirulina platensis in a thermogravimetric analyzer coupled with online mass spectrometry. A hybrid-functional mixture consisting of CaO naturally derived from waste eggshell as catalyst and sorbent, Ni as catalyst and Y2O3 as support was employed during the gasification that mainly generated H2, CO and CO2. The varied CaO loading (10 to 50 wt%) showed an evident effect on the overall gasification of lipid-extracted microalgae biomass, indicating an optimal CaO loading of 40 wt% for Ni-CaO-Y2O3 mixed materials which enabled 400.81 and 324.93 mL g−1 of H2 yield, with maximum purity of up to 53.25 and 41.82 vol% in gaseous product for Chlorella vulgaris and Spirulina microalgae residues, respectively. The addition of Ni, Y2O3 in mixed form (Ni-CaO, Ni-CaO-Y2O3, CaO-Y2O3 and Ni-Y2O3) drastically enhanced H2 yield and its purity. Ni-CaO produced the maximum H2 yield and purity of 497.29 and 435 mL g−1, and 63.15 and 45.78 vol% for Chlorella vulgaris and Spirulina platensis, respectively.

Valorizing petroleum coke into hydrogen-rich syngas through K-promoted catalytic steam gasification

Hydrogen-rich syngas was successfully produced from catalytic steam gasification of petroleum coke. This work studied the steam gasification of petroleum coke over KOH, K2CO3, KNO3, CaO, Fe2O3, K2CO3–CaO and K2CO3–Fe2O3 in a pressurized fixed bed. KOH and K2CO3 demonstrated good catalytic activity compared with other catalysts. The carbon conversion efficiency (CCE) increased from 14.7 wt% to 61.4 wt% and 87.9 wt% after adding 10 wt% K2CO3 and 10 wt% KOH, respectively, and H2 content increased from 60.9 vol% to 66.7 vol% and 64.2 vol%. The increase of gasification temperature and pressure resulted in the increase of CCE. However, raising temperature was beneficial to the increase of H2 and CO contents, while the elevated pressure was in favor of the formation of CH4. In addition, the K-catalytic steam gasification of petroleum coke accorded with the oxygen transfer and intermediate hybrid mechanism.

Steam Gasification of Caking Bituminous Coal using Composite Bimetallic Catalyst

The catalytic steam gasification of Yanzhou (YZ) bituminous coal char loading with K2CO3 and CaO was studied in a fixed bed with 20 mm in inner diameter. The influence of K2CO3 on caking properties of Yanzhou bituminous coal was investigated. The relationship between carbon conversion and reaction time and catalyst loading amount of Yanzhou coal char was measured from 700 to 850°C. The effects of reaction temperature and catalyst loading amount on molar yield of the gasification gas were studied. The influence of catalyst on the microstructure of the YZ coal char was determined. The results show that K2CO3 had significant effects of caking destruction and catalytic gasification on YZ coal. The carbon conversion of YZ coal char increased with the increase of gasification temperature and K2CO3 loading amount. The addition of CaO could improve the carbon conversion of char and promoted the generation of gasification gas to some extent. The molar yield of gasification gas increased with the increase of gasification temperature, and H2 increased the most. The 002 peak of YZ coal char became lower and wider, and moved towards the lower position with the addition of K2CO3 and thus decrease the graphitization trend.

Ru-Promoted Ni/Al2O3 Fluidized Catalyst for Biomass Gasification

Fluidizable catalysts based on Ni/Al2O3 with added Ru were used for the gasification of a lignin surrogate (2-methoxy-4-methylphenol) in a fluidized CREC Riser Simulator reactor. This was done in order to quantify lignin surrogate conversion and lignin surrogate products (H2, CO, CO2 and CH4) as well as the coke deposited on the catalyst. The catalysts that were evaluated contained 5% wt. Ni with various Ru loadings (0.25%, 0.5% and 1% wt). These catalysts were synthesized using an incipient Ni and Ru co-impregnation. Catalysts were characterized using XRD, N2 adsorption-desorption (BET Surface Area, BJH), Temperature Programmed Reduction (TPR), Temperature Programmed Desorption (TPD) and H2 chemisorption. Catalytic steam gasification took place at 550, 600 and 650 °C using 0.5, 1.0 and 1.5, steam/biomass ratios. The results obtained showed that Ru addition helped to decrease both nickel crystallite site sizes and catalyst acid site density. Moreover, it was observed that coke on the catalyst was reduced by 60%. This was the case when compared to the runs with the Ni/Al2O3 free of Ru.

Production of hydrogen-rich gas from waste rigid polyurethane foam via catalytic steam gasification.

Catalytic steam gasification of waste rigid polyurethane foam, in the fixed-bed reactor, was performed to produce hydrogen-rich gas. The influence of nine kinds of additives on the yield of products (gaseous, solid and liquid product) and the volume fraction of hydrogen was investigated. Among the additives, calcium carbonate, as the catalyst, could effectively enhance the gas yield and the volume fraction of hydrogen. A three-factor three-level completely randomised factorial (3 × 3 × 3) design, with calcium carbonate as the catalyst, was applied to investigate the influence of experimental conditions (temperature, steam flowrate and catalyst dosage) on the volume fraction of gaseous product components. The data were processed with SPSS statistical software. The result showed that the main effects of one variable, the interactive effects between two factors and the interactive effects among three factors all have statistical high significance. The best catalysed process is realised when calcium carbonate is the catalyst, gasification temperature is 1100°C, steam flowrate is 0.7 kg h-1, catalyst dosage is 10 wt% of waste rigid polyurethane foam. Under this condition, the volume fraction of hydrogen reaches up to 79.85%.

Direct production of hydrogen-enriched syngas by calcium-catalyzed steam gasification of Shengli lignite/chars: Structural evolution

Calcium has been proved to be efficient for the catalytic steam gasification of lignite. In this study, we studied the steam gasification of lignite with Ca(OH)2 added by wet impregnation for to produce hydrogen. The effect of calcium on the microstructural evolution and char gasification behavior in the presence of steam were studied. The distribution of the gaseous products was examined by using fixed-bed micro reactor equipment for steam gasification. Partially gasified chars obtained at different temperatures (400, 500, 600, and 700 °C) in the gasification process were characterized by scanning electron microscopy coupled with energy dispersive spectroscopy, 13C nuclear magnetic resonance, Fourier-transform infrared spectroscopy, and Raman spectroscopy. The results suggested that a “Ca-carboxylate-like structure” was formed due to the addition of calcium to lignite. This Ca-carboxylate-like structure increased the thermal stability of the original carboxylic structure in lignite. As a result, the calcium-added coal retained more oxygen-containing structures, formed more defects, and possessed significantly lower aromatic structures due to the formed Ca-complexes during steam gasification. Therefore, it can be inferred that the Ca-complexes in the lignite char increased the gasification reactivity of char.

NO and SO2 emissions in palm kernel shell catalytic steam gasification with in-situ CO2 adsorption for hydrogen production in a pilot-scale fluidized bed gasification system

The NO and SO2 emissions in enhanced hydrogen production from palm kernel shell (PKS) steam gasification with integrated catalytic adsorption steam gasification is investigated. The influence of steam and adsorbent to biomass ratios (1.5–2.5, 1.0–1.5), temperature (600–750 °C), biomass particle size (0.355–2.0 mm) and fluidization velocity (0.15–26 m/s) was reported. The results inferred that lower temperature (600 °C) contributed to emissions of NO (30 ppm) and SO2 (110 ppm) whereas high steam to biomass ratio (2.5 wt/wt) produced emissions of <30 ppm and <110 ppm, respectively, at experimental conditions of 675 °C, adsorbent to biomass ratio of 1.0 (wt/wt) and catalyst to biomass ratio of 0.1 (wt/wt). The lowest average minimum NO and SO2 concentration of 16 ppm and 46 ppm, respectively, was observed at 675 °C, steam to biomass ratio of 2.0 (wt/wt), adsorbent to biomass ratio of 1.5 (wt/wt) and catalyst to biomass ratio of 0.1(wt/wt). Nevertheless, emissions were prorportional to fluidization velocities and small particle size (0.3–0.5 mm) contributed to high NO and SO2. The comparative studies found that the present study produced similar emission of NO (30 ppm) when compared with commercial indirect heated fluidized bed gasifier using steam as an oxidizing agent. Besides, some other studies operated at high temperature reported high NO and SO2 concentration which might be due to the temperature being the most influential variable in the context.

Steam gasification of oat hull pellets over Ni-based catalysts: Syngas yield and tar reduction

Renewable and clean energy generated from agricultural crops wastes can displace fossil fuels in heating and power generation. The abundant and low-value byproduct from agricultural industries can have a positive impact on the economy and environment of agricultural provinces in Canada and elsewhere. In this work, the effects of catalytic and non-catalytic steam gasification of oat hull pellets on syngas production and tar reduction were evaluated. For non-catalytic gasification, the impacts of temperature, between 650 and 850 °C, and steam-to-biomass ratio, between 0.25 and 0.50, were tested. Higher temperature increased fuel gas production and heating value, and decreased tar and char yields. Similar effects were observed with increasing steam-to-biomass ratio, except for char yield, which was not affected. For catalytic gasification, Ni/Al2O3 catalysts, with and without Ce, were synthesized and characterized. All catalytic gasification experiments were performed in a two-stage fixed bed reactor at 650 °C and catalyst-to-biomass ratio of 0.5. Among unpromoted catalysts, 10% Ni loading showed the lowest tar formation. Furthermore, adding cerium promoter increased metal dispersion, decreased reduction temperature, and lowered coke formation as observed in TGA. Increasing catalyst to biomass ratio from 0.2 to 1 reduced tar formation from 2.3 to 1.3% but had insignificant influence on syngas yield. As compared to non-catalytic process, using Ni-based catalysts improved the efficiency of steam gasification of oat hull pellets by increasing syngas production and decreasing tar formation. Improving the efficiency will make steam gasification a promising method to convert the agricultural wastes to a clean energy.

Intrinsic kinetics and external diffusion of catalytic steam gasification of fine coal char particles under pressurized and fluidized conditions

Catalytic steam gasification of fine coal char particles was carried out using a self-made laboratory reactor to determine the intrinsic kinetics and external diffusion under varying pressures (0.1–0.5 MPa) and superficial gas flow velocities (GFVs) of 13.8–68.8 cm∙s–1. In order to estimate the in-situ gas release rate at a low GFV, the transported effect of effluent gas on the temporal gasification rate pattern was simulated by the Fluent computation and verified experimentally. The external mass transfer coefficients (kmam) and the effectiveness factors were determined at lower GFVs, based on the intrinsic gasification rate obtained at a high GFV of 55.0 cm∙s–1. The kmam was found to be almost invariable in a wider carbon conversion of 0.2–0.7. The variations of kmam at a median carbon conversion with GFV, temperature and pressure were found to follow a modified Chilton-Colburn correlation: $$Sh = 0.311{\operatorname{Re} {2.83}}S{c^{\frac{1}{3}}}{(\frac{P}{{{P_0}}})^{ - 2.07}}$$ (0.04<Re<0.19), where P is total pressure and P0 is atmospheric pressure. An intrinsic kinetics/external diffusion integrating model could well describe the gasification rate as a function of GFV, temperature and pressure over a whole gasification process.

Catalytic steam gasification of sawdust char on K-based composite catalyst at high pressure and low temperature

The effects of temperature, pressure, steam ratio and K-based composite catalysts on the pressurized steam gasification of sawdust char were studied and the physicochemical structure of composite catalysts was characterized in detail. The results indicated that steam promoted the production of hydrogen but suppressed that of CH4. The generation of CH4 required high pressure, low temperature and suitable steam atmosphere. The composite catalysts reduced the reaction temperature and increased the carbon conversion, theirs catalytic performance ranked in descending order was KCe > KCo > KFe > KNi, where KCe showed perfect catalytic performance, which mainly determined by the ability to activate carbon during pressurized steam gasification of char. KFe and KCo were more conducive to water-gas-shift reaction, while KNi had the better performance on gasification reaction. The transformation paths of the composite catalysts were as follows: Ce(NO3)3·6H2O → CeO2, Co(NO3)2·6H2O → CoO/Co3O4 → Co → CoO, Fe(NO3)3·9H2O → Fe2O3 → FeO → Fe3O4 and Ni(NO3)2·6H2O → NiO → Ni.

Multiple synergistic effects exerted by coexisting sodium and iron on catalytic steam gasification of coal char

Numerous studies have been concerned with inexpensive sodium- and iron-based catalysts for coal gasification. This work aims to investigate the steam gasification of coal char using a Na/Fe bimetallic catalyst. The bimetallic catalyst with an appropriate loading exhibited a higher activity for accelerating the gasification rate than the Na or Fe monometallic catalyst at 700–800 °C. Compared to the sodium catalyst, the bimetallic catalyst was favorable to a higher production of H2 by the reactions with steam. Mechanism study revealed that the coexistence of iron and sodium significantly suppressed the growth of a crystalline Na2CO3 phase and the evaporation of sodium during the gasification leading to the preserve of more sodium as an effective form. Meanwhile, the sodium compounds promoted the reduction of hematite to form α-Fe during the heat-up and the dispersion of iron on the char during the gasification. These interactions were responsible for the transformation of graphitic carbon to amorphous carbon. The bimetallic catalyst could alleviate some shortcomings of the single sodium or iron catalyst.