Combined Steam Reforming Research Articles

Techno-economic assessment and multi-objective optimization of a hybrid methanol-reforming proton exchange membrane fuel cell system with cascading energy utilization

This article proposes an innovative tri-generation system aimed at improving the efficiency of proton exchange membrane fuel cell (PEMFC) combined methanol steam reforming (MSR) setups. The proposed system merges MSR-PEMFC with an organic Rankine cycle (ORC) and Latent-thermal energy storage (LTES) to produce heat, electricity, and purified water concurrently. The MSR process, using methanol and water, acts as a hydrogen source for the PEMFC. Waste heat from the reforming reaction and PEMFC exhaust gases is efficiently recuperated through ORC and LTES. Moreover, a composite phase change material comprising 8 % expanded graphite and 92% industrial paraffin wax is formulated for LTES, exhibiting a thermal conductivity of 4.65 Wm−1K−1. Parametric analysis of the methanol-reforming fuel cell system suggests a methanol to water mass ratio of 1.5 and a pressure swing absorption shunt fraction of 0.77. Multi-objective optimization of the recovery system using the Non-dominated Sorting Genetic Algorithm II algorithm is conducted, with objective functions including tri-generation system exergy efficiency, CO2 emission reduction, and total cost to evaluate system thermodynamic, environmental, and economic performance, respectively. The ORC system employing R245fa and R600 yields 27 % more electricity than the R152a-based system, with exergy efficiencies approximately twice as high. Compared to conventional systems, the proposed tri-generation system achieves an energy efficiency of 81 % and exhibits a 22 % enhancement in energy efficiency.

Electrification pathways for sustainable syngas production: A comparative analysis for low-temperature Fischer-Tropsch technology

The electrification of chemical processes holds promise for a sustainable and climate-neutral chemical industry. This study explores pathways for electrifying syngas production, targeting its utilization in low-temperature Fischer-Tropsch (LT-FT) technology with a hydrocarbon production capacity of 222 kton/yr. Three electrified scenarios are juxtaposed against a reference case of autothermal reforming of biomethane. In the first two scenarios, H2 is produced via water electrolysis, with CO obtained either through CO2 electrolysis (Electrolysis case) or electrified reverse water-gas shift (E-rWGS case). The third scenario leverages captured CO2 and biomethane for electrified combined steam and dry reforming of methane (CSDRM case), exhibiting the lowest net emissions of 0.50 tonCO2/tonproduct. All electrified scenarios achieve net negative emissions under the EU's 2030 target of 40% overall renewable energy production. A detailed techno-economic analysis reveals significant feasibility challenges with the Electrolysis, E-rWGS, and CSDRM cases exhibiting a Levelized Cost Of Production (LCOP) of $501, $457, and $251 per barrel (bbl) of Fischer-Tropsch crude, respectively. Future projections suggest considerable capital cost reductions for electrolyzers, potentially rendering the Electrolysis case feasible, particularly under extremely low electricity prices of 3.3 $/MWh. Careful consideration of green electricity and CO2 utilization scenarios is vital for implementing CO2-negative technologies effectively.

Enhanced activity and stability for combined steam and CO2 reforming of methane over NiLa/MgAl2O4 catalyst

Ni-based catalysts were widely studied for methane reforming system in the past decades, while catalytic deactivation by carbon deposition and metal sintering limited its industrial application life. In this work, La-promoted Ni/MgAl2O4 catalysts were investigated over methane bi-reforming reaction, and significantly improved the activity and stability of catalysts. Multiple characterizations showed that the introduction of La increased the content and dispersion of active species (Ni0), providing sufficient sites for methane adsorption and dissociation. Besides, smaller particle size of active metal (12.6 nm) was proved to inhibiting carbon accumulation on catalyst surface. Ni10La5/MgAl2O4 catalyst was found to exhibit the highest catalytic performance (93% of CH4 conversion, 71% of CO2 conversion and less than 3% activity loss) under long-term reaction conditions (800 °C, 10 h). This work will provide important guiding significance for the design of high-efficiency methane reforming catalysts.

Investigating Reforming Kinetics of a Synthetic Biogas Mixture on Ni: Model Development and Experimental Validation

A thermodynamically consistent mechanistic rate model for steam reforming (SRM) and catalytic partial oxidation (CPOx) of a synthetic biogas mixture on a Ni catalyst is derived in this work. A microkinetic model (MKM) consisting of 42 irreversible reactions served as the starting point for the development of the model equations presented in this study. A global sensitivity analysis based on ANOVA using Sobol sampling is conducted on the MKM to identify important reactions that describe SRM, CPOx, and water–gas shift reaction (WGSR), which occur alongside CH4 reforming. The unimportant reactions are eliminated to obtain a reduced elementary reaction model, which is subjected to validation by reproducing the predictions of 42 reactions of the MKM. The rate-determining steps (rds) are identified for SRM, WGSR, and CPOx, from the reduced mechanism by using a net reaction rate and partial equilibrium analysis. Mechanistic rate expressions are derived from the identified rds by adopting the Langmuir–Hinshelwood–Hougen–Watson approach. The parameters of these mechanistic rate models for SRM, WGSR, and CPOx are estimated by using a real coded genetic algorithm. The rate models with the estimated parameters could reproduce the experimental observations with good accuracy. The predictive capability of the derived rate models is established by comparing the model predictions with the experimental measurements of SRM, combined steam and dry reforming, and trireforming. The reforming experiments were performed for a synthetic biogas mixture containing CH4/CO2 = 2, in a packed bed reactor using 10 wt % Ni/γ-Al2O3. Overall the mechanistic models were able to predict the experimental measurements with good accuracy.

Combined steam and dry reforming of methanol over Ni-M/Ce–Al2O3 (M=Fe, Cu, and Zn) catalysts to syngas formation

In the present work, the influences of different transition metals (Fe, Cu, and Zn) addition to Ni/Ce–Al2O3 catalyst on combined steam and dry reforming of methanol (CSDRM) reaction were evaluated in the temperature range of 500 ºC-900 °C, to achieve the higher conversion and H2 yield following by minimum coke formation on the catalyst surface. The fresh and spent catalysts were characterized via X-ray diffraction (XRD), thermal gravimetric analysis (TGA), inductively coupled plasma atomic emission spectrometer (ICP-AES), temperature programmed oxidation (TPO), N2 adsorption/desorption and temperature programmed reduction (TPR). Their results presented that the addition of these transition metals had a little effect on the crystallinity, surface area, pore volume and mean pore size. However, thermal stability, coke deposition coke amount, reducibility and catalytic activity were improved. The methanol conversion was approximately fixed up to 50 h initial on stream with no obvious deactivation for Ni/Ce–Al2O3 catalyst, while this time was 55 h for the modified catalyst with transition metals (Cu, Fe, and Zn). The maximum methanol and CO2 conversions and anti-coke deposition ability were obtained from Ni–Zn/Ce–Al2O3 which was remarkably related to synergism between Ni and Zn, also the larger reducibility. However, the maximum value of H2 yield was 85.2% at 900 °C over Ni–Cu/Ce–Al2O3 catalyst. Ni–Zn/Ce–Al2O3 catalyst in the CSDRM reaction produced syngas with an H2/CO ratio of 2.06, suggesting to a suitable feed for Fischer-Tropsch synthesis.

Combined Steam and CO2 Reforming of Methane over Ni-Based CeO2-MgO Catalysts: Impacts of Preparation Mode and Pd Addition

The sol–gel template technique makes it possible to synthesize a stable and efficient nickel catalyst based on magnesium-modified cerium oxide Ce0.5Mg0.5O1.5 for the combined steam and CO2 reforming of methane. To stabilize dispersed forms of the active component in the matrix of the support, the catalysts were synthesized by changing the support precursor (cerium acetate and chloride), the active component composition (Ni, NiPd) and the method of introducing nanoparticles. The relationship was established between the physicochemical and catalytic characteristics of the samples. The use of cerium acetate as a support precursor provided smaller pore and crystallite sizes of the support, a stabilization of the dispersed forms of the active component, and excellent catalytic characteristics. The introduction of Pd into the Ni nanoparticles (Pd/Ni = 0.03) increased the resistance of the active component to sintering during the reaction, ensuring stable operation for 25 h of operation. The increased stability was due to a higher concentration of defective oxygen, a higher dispersion of bimetallic NiPd nanoparticles, and the Ni clusters strongly interacting with the NiO-MgO solid solution. An efficient and stable Ni0.194Pd0.006Ce0.4Mg0.4O1.4 catalyst for the conversion of CO2 into important chemicals was developed. With the optimal composition and synthesis conditions of the catalyst, the yield of the target products was more than 75%.

Use of A-Site Metal Exsolution from a Hydrated Perovskite Titanate for Combined Steam and CO2 Reforming of Methane.

Metal segregation from a perovskite oxide (ABO3) usually referring to "redox metal exsolution" has recently been used for in situ preparation of a well-designed catalyst where metal nanoparticles are homogeneously and strongly embedded on perovskite scaffolds upon reduction. The exsolution concept of B-site transition metal ions has grown, but several issues such as segregation of A-site alkaline-earth metal ions (altering electronic structures of the perovskite surface, causing deformation of perovskite structures, or creating undesirable products via side reactions) and carbon formations on metal nanoparticles should be addressed for stable catalysts in greenhouse gas (CO2 or CH4) conversion. Here, we suggest a new approach to designing metal-perovskite composite catalysts via A-site metal segregation from a hydrated perovskite titanate. In situ formation of A-site-deficient hydrated CaTiO3 accompanied with Ni exsolution solids leads to ∼78 and 65% of CH4 and CO2 conversion, respectively, suppressing carbon formations and alkaline-earth metal segregations in combined steam and carbon dioxide reforming of methane at 700 °C. It would help to design active and stable metal-perovskite catalysts for energy and environmental applications.

Hydrogen Production in Catalytic Membrane Reactors Based on Porous Ceramic Converters

This article presents the results of the development of membrane-catalytic methods for obtaining purified hydrogen of various degrees of purity required for feeding high-, medium-, and low-temperature fuel cells. In order to conduct this, porous ceramic catalytic converters were obtained using self-propagating high-temperature synthesis. These converters are suitable for high-speed processes for producing synthesis gas with different carbon monoxide content (0.08–0.1 vol. %), which can be used to feed fuel cells of various types. Using a hybrid catalytic membrane reactor, in which the stage of catalytic conversion of organic substrates was combined with the stage of selective extraction of ultrapure hydrogen (content of H2 was not less than 99.9999 vol. %) from the reaction zone, combined carbon dioxide and steam reforming of organic substrates of various origins were carried out. The result of the work was the creation of a prototype of a small-sized electric generator plant in which a catalytic membrane reactor was combined with a solid-oxide fuel cell.

Combined steam and dry reforming of methanol process to syngas formation: Kinetic modeling and thermodynamic equilibrium analysis

In the present study, the combined steam and dry reforming of methanol (CSDRM) process were performed in the temperature range of 400 °C-900 °C, CO2/H2O ratio of 0.5–2.5 and (CO2+H2O)/CH3OH ratio of 0.5–2.5 at the atmospheric pressure over a Pt/ZrO2 catalyst in fixed bed reactor. The experimental data was applied to model the kinetic of CSDRM reaction based on Langmuir-Hinshelwood (LH) isotherm with one active site on the catalyst surface taking into account. By comparing the two experimental and calculated values, it was seen that error of kinetic model in predicting the experimental methanol conversion was lower (7.97%) than other responses. An almost completed methanol conversion was attained above 800 °C at all values of CO2/H2O ratios except for (CO2 + H2O)/CH3OH ratio of 0.5. The temperature had a positive impact on the H2 and CO yields, however; the dependency of CO yield to temperature was higher than H2 yield. CO2 conversion slightly decreased from 400 °C to 500 °C, while started to increase at temperatures above 500 °C regardless of (CO2+H2O)/CH3OH and CO2/H2O ratios. H2/CO ratio near to 2 which is suitable for Fischer–Tropsch synthesis (FTS) reaction was obtained at (CO2+H2O)/CH3OH ratios bigger than 1.5, a CO2/H2O ratio of 1 and temperature above 800 °C. The methanol conversion values obtained from thermodynamic equilibrium were equal with the experimental data. The reverse water-gas shift reaction quickly happened at temperatures above 700 °C, higher values of CO2/H2O ratio and under excess oxidizing agent, which led to increasing the gap between the experimental data and measured from thermodynamic equilibrium analysis.

Effect of Support on Stability and Coke Resistance of Ni-Based Catalyst in Combined Steam and CO2 Reforming of CH4.

Ni-based catalysts dispersed on different supports (MgO-α-Al2O3, CeO2, SBA-15, and MgO-SBA-15) were prepared by the impregnation method. Characteristics of the catalysts, including specific surface areas (N2 physisorption), crystalline phase compositions (powder X-ray diffraction, Raman spectroscopy), reducibility (hydrogen temperature-programmed reduction, H2-TPR), and morphology (scanning electron microscopy (SEM) and transmission electron microscopy, TEM)) were investigated. The activity and stability of the catalysts were tested for the combined steam and CO2 reforming of methane at 700 °C in a microflow system. The results show that the catalysts exhibit high activity in the BRM reaction. At 700 °C, the conversion of CH4 and CO2 reached 86–99% and 67–80%, respectively, in which the Ni/Mg–SBA catalyst is the best with conversions of CH4 and CO2 reaching 99% and 80%. Coke accumulation on the surface of the catalysts for 100 h time on stream (TOS) was evaluated by the temperature-programmed oxidation (TPO) technique. The major cause of the catalytic deactivation was elucidated by combining the determination of the amount and type of deposited coke with the changes in the physicochemical properties of the catalysts after the long-term reaction. Almost complete loss of activity was observed on Ni/Mg–Al catalyst after 100 h TOS, while the activity drop was slow on the Ni/Mg–SBA sample, about 15–20% of the total value. Otherwise, the Ni/CeO2 and Ni/SBA catalysts firmly retained their stable activity for 100 h TOS due to the minimal carbon deposition and stability of these catalysts’ structure. The highly considerable formation of inert Cγ carbon and sintering over Ni catalyst supported on MgO-α-Al2O3 were responsible for the lower stability of this catalyst compared to those supported on CeO2 and SBA-15.

Combined steam and CO2 reforming of methane over Co–Ce/AC-N catalyst: Effect of preparation methods on catalyst activity and stability

An appropriate preparation method is the essential to improve the catalyst performance. In this study, Co–Ce/AC-N catalysts were fabricated on N-doped activated carbon supports by impregnation, sol-gel, precipitation and mix methods, respectively. It was used to catalyze the combined steam and dry reforming of methane (CSDRM). The effects of different preparation methods on the catalyst performance were investigated by means of N2 adsorption-desorption, XRD, H2-TPR, TEM, CO2-TPD, FTIR and XPS. Compare with the catalysts prepared by other methods, the catalyst prepared by impregnation exhibits a large surface area, high active metal dispersion, and strong metal-support interaction. Meanwhile, it also has strong basic sites and abundant oxygen vacancies. These greatly improve the activity and stability of the catalyst. The conversions of CH4 and CO2 at 650 °C were achieved 71.6% and 64.4%, and H2/CO was retained at 1.5.

The Effect of ZrO2 as Different Components of Ni-Based Catalysts for CO2 Reforming of Methane and Combined Steam and CO2 Reforming of Methane on Catalytic Performance with Coke Formation

The role of ZrO2 as different components in Ni-based catalysts for CO2 reforming of methane (CRM) has been investigated. The 10 wt.% Ni supported catalysts were prepared with ZrO2 as a support using a co-impregnation method. As a promoter (1 wt.% ZrO2) and a coactive component (10 wt.% ZrO2), the catalysts with ZrO2 were synthesized using a co-impregnation method. To evaluate the effect of the interaction, the Ni catalyst with ZrO2 as a coactive component was prepared by a sequential impregnation method. The results revealed that the activity, the selectivity, and the anti-coking ability of the catalyst depend upon the ZrO2 content, the Ni-ZrO2 interaction, basicity, and oxygen mobility of each catalyst resulting in different Ni dispersion and oxygen transfer pathway from ZrO2 to Ni. According to the characterization and catalytic activation results, the Ni catalyst with low ZrO2 content (as a promoter) presented highest selectivity toward CO owning to the high number of weak and moderate basic sites that enhance the CO2 activation-dissociation. The lowest activity (CH4 conversion ≈ 40% and CO2 conversion ≈ 39%) with the relatively high quantity of total coke formation (the weight loss of the spent catalyst in TGA curve ≈ 22%) of the Ni catalyst with ZrO2 as a support is ascribed to the lowest Ni dispersion due to the poor Ni-ZrO2 interaction and less oxygen transfer from ZrO2 to the deposited carbon on the Ni surface. The effect of a poor Ni-ZrO2 interaction on the catalytic activity was deducted by decreasing ZrO2 content to 10 wt.% (as a coactive component) and 1 wt.% (as a promoter). Although Ni catalysts with 1 wt.% and 10 wt.% ZrO2 provided similar oxygen mobility, the lack of oxygen transfer to coke during CRM process on the Ni surface was still indicated by the growth of carbon filament when the catalyst was prepared by co-impregnation method. When the catalyst was prepared by a sequential impregnation, the intimate interaction of Ni and ZrO2 for oxygen transfer was successfully developed through a ZrO2-Al2O3 composite. The interaction in this catalyst enhanced the catalytic activity (CH4 conversion ≈ 54% and CO2 conversion ≈ 50%) and the oxygen transport for carbon oxidation (the weight loss of the spent catalyst in TGA curve ≈ 7%) for CRM process. The Ni supported catalysts with ZrO2 as a promoter prepared by co-impregnation and with ZrO2 as a coactive component prepared by a sequential impregnation were tested in combined steam and CO2 reforming of methane (CSCRM). The results revealed that the ZrO2 promoter provided a greater carbon resistance (coke = 1.213 mmol·g−1) with the subtraction of CH4 and CO2 activities (CH4 conversion ≈ 28% and CO2 conversion ≈ %) due to the loss of active sites to the H2O activation-dissociation. Thus, the H2O activation-dissociation was promoted more efficiently on the basic sites than on the vacancy sites in CSCRM.

Investigating the influence of operating conditions on the combined steam and carbon dioxide reforming of methane performance in the presence of Ni/ZrO2 catalyst

In the present study, Ni/ZrO2 catalyst was synthesized via co-precipitation approach and its catalytic activity was evaluated in combined steam and carbon dioxide reforming of methane (CSCRM) reaction at a temperature range of 773 K–1273 K, CO2:H2O ratio of 0.5-3 and (CO2 + H2O)/CH4 ratio of 0.5-3. The results demonstrated that the higher (CO2+H2O)/CH4 ratio and temperature were required for CH4 conversion about 100%. The effect of CO2/H2O ratio was little on the CO and H2 yield. A (CO2+H2O)/CH4 ratio of 1.5 associated with CO2/H2O ratio of 0.5 at the minimum temperature of 1073 K were the required reaction conditions for the synthesis gas (syngas) formation with H2/CO ratio about 2. The temperature, type and amount of the oxidizing agent greatly affected on the amount of coke deposition. The least temperature of 1073 K and (CO2+H2O)/CH4 ratio higher than 1.5 irrespective of CO2:H2O ratio was obtained as a proper operation conditions to avoid coke formation. Moreover, CO2 revealed a higher portion than H2O in coke formation in CSCRM reaction.

Effect of NH3 Alkalization and MgO Promotion on the Performance of Ni/SBA-15 Catalyst in Combined Steam and Carbon Dioxide Reforming of Methane

In this work, 31.4 wt.% Ni/SBA-15 (Ni/SBA-15) nonpromoted and alkalized with ammonia solution and by MgO promoter catalysts were prepared and used for combined steam and CO2 reforming of CH4 (bireforming). Effect of concentration of ammonia solution (NH3(aq)) (10–25 vol.%) and Mg content (3–12 wt.%) on the properties of the Ni/SBA-15 catalysts was investigated by low-angle and powder X-ray diffraction (XRD), N2-BET isothermal adsorption, SEM, TEM, EDS mapping, H2-TPR, and CO2-TPD methods. The performance of the catalysts in bireforming was assessed in the temperature range of 550–800°C. The enhancement of dispersion of NiO particles, reducibility, and basicity of alkalized Ni/SBA-15 catalysts were responsible for improving the catalytic performance of this catalyst. The results revealed that the Ni/SBA-15 treated with 15-25% NH3(aq) solution and promoted with 3-9% Mg exhibited high activity for CH4 conversion. Meanwhile, Ni6Mg/SBA-15 showed the highest CO2 conversion. Among tested catalysts, Ni/SBA-15-20NH3 and Ni9Mg/SBA-15 samples had an almost equal activity with a CH4 conversion of nearly 97% and a CO2 conversion of about 84% at 700°C thanks to its moderate affinity with both CO2 and CH4. However, the H2/CO ratio of the product mixture remained at 2.02 on the Ni/SBA-15-20NH3 catalyst and almost 1 on the Ni9Mg/SBA-15 sample. These results might be related to the fact that the alkalization of the Ni/SBA-15 catalyst by NH3(aq) solution had an advantage over using MgO because side reactions were unlikely to occur.

Characteristics and activity of Ni/CeO<sub>2</sub> catalyst modified by Cr<sub>2</sub>O<sub>3</sub> in combined steam and CO2 reforming of CH4

A series of 10%wtNiO/CeO2-nanorod catalyst without and with Cr2O3 additive was prepared by simultaneous impregnation method. Several techniques, including N2 physisorption measurements, X-ray powder diffraction (XRD), temperature-programmed reduction using H2 (H2-TPR), CO2 temperature-programmed desorption (CO2-TPD), scanning electron microscope (SEM) and transmission electron microscopy (TEM) were used to investigate catalysts’ physico-chemical properties. The activity of the catalysts in combined steam and CO2 reforming of CH4 (BRM) was investigated at temperature range of 550-800 °C. The results showed that 10%NiO0.1%Cr2O3/CeO2 catalyst had the best catalytic performance due to a better reducibility and basicity. At 700 °C and CH4:CO2:H2O molar ratio in feed stream of 3:1.2:2.4, both conversion of CH4 and CO2 on this catalyst reached 98.5%.

A comprehensive review on improving the production of rich-hydrogen via combined steam and CO2 reforming of methane over Ni-based catalysts

During the last few decades, the global energy requirement is soaring significantly due to the rise of global population and economic development. This resulted in colossal release of CO2 and CH4, emissions into the atmosphere referred as greenhouse gases (GHGs), which poses a detrimental effects for the environment. One of the sustainable solutions to curb emissions of GHGs into the atmosphere is efficient utilization of syngas in order to produce useful chemicals and fuels. A comprehensive review is presented to highlight the capability of Ni-based catalysts in methane reforming through the application of both steam and dry routes referred to as bi-reforming of methane (BRM). Ni-based catalysts were found to support favorable reaction activity as they are cheaper than many exorbitant catalysts. The metal used for catalyst support exhibits higher stability and thermal resistance with improved resistance to coke formation. This review entails recent progresses in the development of Ni-based catalysts along with physical and kinetic aspects of the BRM process.

Deactivating and Non-Deactivating Coking Found on Ni-Based Catalysts during Combined Steam-Dry Reforming of Methane

Management of coke formation during the dry reforming (DRM) and combined steam reforming (CSDRM) of methane is a crucial key towards the control of catalyst performance of such processes. Hence, this work provided a fundamental understanding of coke and coking to achieve the desire performance for the Ni-based catalysts typically employed in the industrial via the control over the formation of deactivating coke – amorphous (Cβ), carbide (Cγ), and graphitic coke (CC) that associated directly to the catalyst performance. Therefore, it is demonstrated that during DRM and CSDRM, a low reaction temperature would result in a conversion that is too low to be a practical process, while around 600 °C, the Ni carbide (Cγ) would form in high quantity, and operating up to 800 °C will cause the catalyst performance to drop significantly due high amount of graphitic coke. The CSDRM process compared to DRM can reduce the deactivating coke from 25 – 38% to 2.5 – 21.4% on the Ni-based catalysts. This positive effect on coke-resistant is the elimination of Cβ formation, which is the reactant for the graphitic carbon formation, resulting in a decrease in the overall amount of deactivating coke. Hence, we suggested that one select CSDRM over DRM due to the promotional effect of steam associated with the mitigation of the total deactivating coke via the blocking of amorphous coke formation and the appropriate temperature prevent Cγ and CC formation.

Combined Steam and Carbon Dioxide Reforming of Methane Using Nickel-Based Catalysts: Effects of Synthesis Method, Promoter, Space Velocity and Pressure

The effects of Rh and MgO addition, weight hourly space velocity (WHSV: 20000 ~ 100000 ml/h·g cat ), and pressure (0.1 ~ 10 barg) on the combined steam and carbon dioxide reforming of methane (CSCRM) were investigated using Ni supported on Al 2 O 3 . In addition, the Ni/Al 2 O 3 samples produced by the freeze drying (FD) and oven drying (OD) methods were compared to improve the activity and high-temperature stability. FD obtained a higher surface area, higher metal dispersion, and smaller Ni crystallite size than those obtained by OD. The resistance to carbon deposits was improved using the FD method. In the CSCRM, the higher the WHSV and pressure, the lower catalyst activity. However, Rh-Ni/MgO-Al 2 O 3 showed the smallest carbon deposits and the highest activity, and exhibited high stability in a long-term reaction that lasted 36 h. This study can provide basic data for the CSCRM demonstration process.

A Study of Thermodynamic Equilibrium Analysis and Optimized Reaction Conditions for Combined Steam Reforming of Biogas

A Study of Thermodynamic Equilibrium Analysis and Optimized Reaction Conditions for Combined Steam Reforming of Biogas

Ni-based catalysts supported on MgAl2O4 with different properties for combined steam and CO2 reforming of methane

Three MgAl2O4 spinels were prepared by co-precipitation (cp), sol–gel (sg) and alcoholysis (al) methods, and used as supports for Ni catalysts for combined steam and CO2 reforming of methane (CSCRM). MgAl2O4(cp), MgAl2O4(sg) and MgAl2O4(al) showed different textural, morphological and chemical properties. By comparison of the properties of MgAl2O4 with those of 10Ni/MgAl2O4 (10 wt% Ni loading), it was found that the basicity of MgAl2O4 was a major factor influencing not only the basicity of catalyst but also the Ni particle size and dispersion. MgAl2O4(sg) possessed the highest amount of basic sites leading to 10Ni/MgAl2O4(sg) having the strongest basicity and the smallest Ni particle size. These properties bestowed 10Ni/MgAl2O4(sg) with superior anti-coking and anti-sintering properties as well as the highest activity and stability for CSCRM among all catalysts including 10Ni/MgO and 10Ni/γ-Al2O3. Further investigations on the effect of Ni loading (5–15 wt%) showed that 10Ni/MgAl2O4(sg) was the best catalyst for CSCRM, with stable conversions of CH4 (88.9%) and CO2 (68.6%) over 30 h on stream (CH4:H2O:CO2 = 2.5:2:1 (molar ratio)) at 800 °C, 0.1 MPa and a gas hourly space velocity of 132,000 NmL/(gcat·h).