Catalytic Steam Research Articles

Lab-Scale Investigation of Palm Shell Char as Tar Reforming Catalyst

This research investigated the application of palm shell char as a catalyst for the catalytic steam reforming of tar after the sorption enhanced gasification (SEG) process. The catalytic activities of palm shell char and metal-supported palm shell char were tested in a simulated SEG derived syngas with tar model compounds (i.e., toluene and naphthalene) at a concentration of 10 g m−3 NTP. The results indicated that palm shell char had an experimentally excellent catalytic activity for tar reforming with toluene and naphthalene conversions of 0.8 in a short residence time of 0.17 s at 900 °C. A theoretical residence time to reach the complete naphthalene conversion was 1.2 s at 900 °C for palm shell char, demonstrating a promising activity similar to wood char and straw char, but better than CaO. It was also found that potassium and iron-loaded palm shell chars exhibited much better catalytic activity than palm shell char, while the parallel reaction of gasification of K-loaded palm shell char influenced the conversion with its drastic mass loss. Moreover, contrary to CaO, palm shell char presented relatively low selectivity to benzene, and its spontaneous gasification generated extra syngas. In summary, the present study demonstrated that the low-cost material, palm shell char, can successfully be used as the tar-reforming catalyst after SEG process.

Review of Recent Aromatic–Aliphatic–Ionic Liquid Ternary Liquid–Liquid Equilibria and Their Modeling by COSMO-RS

Separation of aromatics from aliphatics following catalytic reforming or steam cracking processes is difficult and energy intensive, even with highly optimized extraction solvents like sulfolane. A...

Hydrogen production via steam reforming of coke oven gas enhanced by steel slag-derived CaO

Steel slag, a waste from steelmaking plant, has been proven to be good candidate resources for low-cost calcium-based CO2 sorbent derivation. In this work, a cheap and sintering-resistance CaO-based sorbent (CaO (SS)) was prepared from low cost waste steel slag and was applied to enhance catalytic steam reforming of coke oven gas for production of high-purity hydrogen. This steel slag-derived CaO possessed a high and stable CO2 capture capacity of about 0.48 g CO2/g sorbent after 35 adsorption/desorption cycles, which was mainly ascribed to the mesoporous structure and the presence of MgO and Fe2O3. Product gas containing 95.8 vol% H2 and 1.4 vol% CO, with a CH4 conversion of 91.3% was achieved at 600 °C by steam reforming of COG enhanced by CaO (SS). Although high temperature was beneficial for methane conversion, CH4 conversion was remarkably increased at lower operation temperatures with the promotion effects from CaO (SS), and CO selectivity has been also greatly decreased. Reducing WHSV could increase methane conversion and reduce CO selectivity due to longer reactants residence time. Reducing C/A could increase methane conversion and hydrogen recovery factor, and also decrease CO selectivity. When being mixed with catalyst during SE-SRCOG, CaO (SS) with a uniform size distribution favored methane conversion due to the high utilization efficiency of catalyst. Promising stability of CaO (SS) in cyclic reforming/calcination tests was evidenced with a hydrogen recovery factor >2.1 and CH4 conversion of 82.5% at 600 °C after 10 cycles using CaO (SS) as sorbent.

Catalytic steam reforming of tar for enhancing hydrogen production from biomass gasification: a review

Presently, the global search for alternative renewable energy sources is rising due to the depletion of fossil fuel and rising greenhouse gas (GHG) emissions. Among alternatives, hydrogen (H2) produced from biomass gasification is considered a green energy sector, due to its environmentally friendly, sustainable, and renewable characteristics. However, tar formation along with syngas is a severe impediment to biomass conversion efficiency, which results in process-related problems. Typically, tar consists of various hydrocarbons (HCs), which are also sources for syngas. Hence, catalytic steam reforming is an effective technique to address tar formation and improve H2 production from biomass gasification. Of the various classes in existence, supported metal catalysts are considered the most promising. This paper focuses on the current researching status, prospects, and challenges of steam reforming of gasified biomass tar. Besides, it includes recent developments in tar compositional analysis, supported metal catalysts, along with the reactions and process conditions for catalytic steam reforming. Moreover, it discusses alternatives such as dry and autothermal reforming of tar.

High purity H2 production from sorption enhanced bio-ethanol reforming via sol-gel-derived Ni–CaO–Al2O3 bi-functional materials

Catalytic steam reforming of renewable bio-oxygenates coupled with in-situ CO2 capture is a promising option for sustainable H2 production. The current work focuses on high purity H2 production over Ni–CaO–Al2O3 bi-functional materials via sorption enhanced steam reforming of ethanol (SEESR). To ensure the uniform distribution of catalytic sites (Ni), adsorptive sites (CaO) and stabilizer (Al2O3) in the bi-functional materials, a citrate sol-gel synthetic route was employed. These materials were characterized by XRD, N2 physical adsorption, SEM, TG and TPR techniques. It was revealed that the existence of CaO in bi-functional materials could not only in-situ remove CO2, but also play the role of inhibiting the formation of harmful spinel phase. The stabilizing role of Al component against capacity decay was confirmed, whereas the presence of Ni ions had a negative effect on the cycle CO2 uptake. The sample of Ni/Al/Ca-85.5 possessed large specific surface area, abundant porosity with fluffy morphology, and thereby, exhibited the best CO2 sorption capacity during 20 carbonation/calcination cycles. The highest H2 concentration of 96% was obtained through the SEESR during the pre-breakthrough period when the Ni/Al/Ca-85.5 was employed. Over the optimized bi-functional material, the effect of operating conditions on the SEESR was investigated and the results indicated that temperature of 600 °C, reaction liquid space velocity of 0.05 ml/min and steam/ethanol ratio of 4 were the suitable conditions. After 10 cycles, the bi-functional material of Ni/Al/Ca-85.5 also showed the best performance, with a H2 purity of about 90% and pre-breakthrough time of 18 min, conforming the high potential of this material for SEESR process.

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.

Hydrogen Production from Catalytic Steam Reforming of Bio‐Oils: A Critical Review

AbstractIn the future, hydrogen will be an important energy carrier and industrial raw material. Catalytic steam reforming of bio‐oils is a promising and economically viable technology for hydrogen production. However, during the reforming process, the catalysts are rapidly deactivated due to coke formation and sintering. Thus, maintaining the activity and stability of catalysts is the key issue in this process. Optimized operation conditions could extend the catalyst lifetime by affecting the coke morphology or promoting coke gasification. This article summarizes the recent developments in the field of catalytic steam reforming of bio‐oils, focusing on the operation conditions, the properties of the catalysts, and the effects of the catalyst supports. The expected insights into the catalytic steam reforming of bio‐oils will provide further guidance for hydrogen production from bio‐oils.

Effect of in-situ and ex-situ injection of steam on staged-gasification for hydrogen production

K modified Ni-based catalysts are used to investigate the effect of in-situ and ex-situ injection of steam (ISI and ESI) on biomass pyrolysis and in-line catalytic steam reforming in a two-stage fixed bed reactor. The results show that 0.5 wt% K is appropriate to modify the Ni-based catalysts for steam reforming of biomass pyrolysis vapor. Compared to the catalytic cracking without steam addition, both ISI and ESI increase the gas yield and the carbon conversion efficiency (Xc) of the pyrolysis vapors. And the ESI is more beneficial to the conversion of pyrolysis vapors to small molecular gases. The maximum hydrogen concentration, hydrogen yield and carbon conversion efficiency (Xc) of staged-gasification can reach 53.8%, 31 mmol/g-bio, and 94.6%, respectively, when both stages are at 700 °C with ex-situ steam injection (S/C = 1.2) and 3 g catalyst loaded in the second stage. Also, the steam is beneficial to removing the depositions of graphitized coke and small molecular polycyclic aromatic hydrocarbon on the catalysts. However, it is yet difficult for steam to react with the highly ordered carbonaceous.

Comprehensive Modeling of Sorption-Enhanced Steam Reforming of Coke Oven Gas in a Fluidized Bed Membrane Reactor

Integration of membrane hydrogen separation and carbon dioxide capture with fuel steam reforming efficiently promote hydrogen production and feedstock conversion. In this study, catalytic steam reforming of coven oven gas in a sorption-enhanced fluidized bed membrane reactor (MA-SE-SRCOG) was simulated using a reactive three-fluid model under Euler framework. The numerical studies provided insights into details about interactions of multi-scale sub-processes, including hydrogen permeation, carbon dioxide adsorption, catalytic reforming and multiphase flow dynamics, during MA-SE-SRCOG. Concentration polarization caused by hydrogen separation was also examined. Meanwhile, impacts of several operating parameters, such as reaction pressure, steam concentration, membrane position and reactor scale, on the performances of MA-SE-SRCOG were evaluated in terms of CH4 conversion, CO selectivity, hydrogen recovery factor and CO2 fix factor. The simulation results demonstrated that membrane hydr...

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.

Catalytic Steam Reforming of Natural Gas over a New Ni Exsolved Ruddlesden‐Popper Manganite in SOFC Anode Conditions

AbstractThe catalytic behavior of the new Ni exsolved Ruddlesden‐Popper (RP) manganite (La1.5Sr1.5Mn1.5Ni0.5O7) for the reforming reaction was studied. The material was synthesized by the Pechini method and reduced to induce the formation of two phases: n=1 RP structure LaSrMnO4 decorated with Ni nanoparticles. Ni impregnation on (La,Sr)2MnO4 ceramic support of similar composition was also prepared for comparison. The catalytic measurements were carried out in a reduction‐reaction process with low steam to carbon content (S/C=0.15) at 700, 800 and 850 °C. The exsolved material exhibits a better performance than the impregnated for the methane steam reforming reaction, especially at 850 °C with higher conversion and H2 production rate. However, in light alkane gas mixtures (CH4−C2H6 and CH4−C3H8), the behavior is affected due to the competition between reactions and low available metallic active sites, without affecting the H2 production. The exceptional overall results considering this new material as a promising anode material in a SOFC fed with Colombian natural gas.

Effects of metal cation doping in CeO2 support on catalytic methane steam reforming at low temperature in an electric field.

Catalytic methane steam reforming was conducted at low temperature using a Pd catalyst supported on Ce1−xMxO2 (x = 0 or 0.1, M = Ca, Ba, La, Y or Al) oxides with or without an electric field (EF). The effects of the catalyst support on catalytic activity and surface proton hopping were investigated. Results show that Pd/Al-CeO2 (Pd/Ce0.9Al0.1O2) showed higher activity than Pd/CeO2 with EF, although their activity was identical without EF. Thermogravimetry revealed a larger amount of H2O adsorbed onto Pd/Al-CeO2 than onto Pd/CeO2, so Al doping to CeO2 contributes to greater H2O adsorption. Furthermore, electrochemical conduction measurements of Pd/Al-CeO2 revealed a larger contribution of surface proton hopping than that for Pd/CeO2. This promotes the surface proton conductivity and catalytic activity during EF application.

Catalytic steam reforming of JP-10 over Ni/SBA-15

As the only H2 resource on aircraft from the steam reforming of the jet fuels on board, catalytic steam reforming of JP-10 (one of Jet fuels) over nickel-based catalyst Ni/SBA-15 were first carried out in a fixed bed tube reactor to produce hydrogen on-site or on board. A series of Ni/SBA-15 catalysts with different Ni content (3, 5, 8 and 10.8 wt%) were prepared by a modified incipient wetness impregnation method with addition of sucrose as ligand. And the effect of operation conditions of temperature (630–700 °C), nickel loading, liquid hour space velocity (LHSV = 5, 10, 15 ml/gcat·h), steam to carbon molar ratio (S/C = 3, 5) on the catalytic activity and selectivity was investigated. It was found that 8Ni/SBA-15 was the optimal catalyst for steam reforming of JP-10 even with a higher LHSV and fuel gas concentration, and approximately 100% conversion of JP-10 with over 80% selectivity to hydrogen under the recommended experimental conditions of 680 °C, S/C of 5, LHSV of 10 ml/gcat·h. The catalytic activity of 8Ni/SBA-15 dropped slowly to 84% after 6.5 h in the stability test and the carbon deposited was less with just 6% mass loss from TGA measurement (coke deposition rate 0.01gC/gcath), which ascribed to possible reasons including confine effect of mesochannel of SBA-15, strengthened structure of mesochannels due to embeded Ni particles, and higher temperature to suppress the main carbon producing reaction.

Comparative study on the catalytic steam reforming of biomass pyrolysis oil and its derivatives for hydrogen production.

In order to explore the reforming process of biomass pyrolysis oil in depth, the catalytic steam reforming (SR) of crude bio-oil (BIO) derived from rapid pyrolysis of rice husk and its derivatives for hydrogen production was studied by means of a bench-scale fixed-bed unit combined with the FTIR/TCD technique. The physico-chemical properties and compositions of BIO were determined. Acetic acid (HOAc), ethylene glycol (EG), acetone (ACE) and phenol (PHE) were selected as four representative bio-oil derivatives. Evolution characteristics of H2, CO, CO2 and CH4 during SR of HOAc, EG, ACE, PHE and BIO were revealed and compared. The hydrogen yield increased sharply with reaction time to the peak values of 24.7%, 32.3%, 16.4%, 25.6% and 24.9%, corresponding to HOAc, EG, ACE, PHE and BIO, respectively. After that, the yield of hydrogen exhibited a downward trend, suggesting that the catalyst ability for selective hydrogen production gradually decreased. The H2 yield from EG was the highest, followed by PHE, HOAc, BIO and ACE. The order of CO yields from large to small was EG > HOAc > ACE > BIO ≈ PHE. The percentages of coke deposited on catalyst were arranged in descending order as HOAc > BIO > ACE > PHE > EG. This study could provide more detailed information on the catalytic reforming mechanism of bio-oil on the one hand, and also point out the direction for the improvement of the catalysts, which play a role in ensuring the high yield of H2 while converting CO to H2 through the water gas shift reaction.

Evaluation of plasma-derived heat and synergistic effect for in-plasma catalytic steam reforming of methanol

How to evaluate plasma-derived heat (PDH) and the synergistic effect of plasma catalysis, especially for in-plasma catalysis (IPC), is still ambiguous. In this work, to exclude the reaction-heat impact on PDH, N2 plasma was first used to compare the heat-uninsulated and heat-insulated cases for empty and packed dielectric barrier discharge (DBD). Compared with the heat-uninsulated cases, the heat-insulation has nearly the same discharge characteristics, and a weak impact on N2 rotational temperature. The heat-insulation, whether for empty or packed DBD, gave much higher outgoing gas temperature (Tg) and reactor wall temperature (Tw) than the heat uninsulation. For methanol-steam reforming in the heat-insulated reactor over various supported catalysts on Al2O3 support (AS), the dependence of PDH indicated by Tw on reaction-heat power was observed. The synergistic effect of plasma and Au/CeZn/AS catalyst in the heat-insulated IPC reactor was verified. For the plasma alone case, methanol conversion was negligible, giving a Tw of 618 K. For the IPC case, the Tw decreased considerably to 545 K due to the effect of reaction-heat power on PDH. Methanol conversion of 46.8% was achieved, which is much higher than the catalysis alone case of 9.0%, even at a higher temperature of 573 K. Moreover, H2 selectivity increased from plasma alone from 80.0% to 95.1%. If the IPC case was heat-uninsulated, the Tw dropped down to 385 K, and accordingly methanol conversion became insignificant. This work demonstrated that heat-insulation is necessary for reliable evaluation of the PDH and the synergistic effect in plasma catalysis.

Thermal management evaluation for advanced aero-engines using catalytic steam reforming of hydrocarbon fuels

The wall catalytic steam reforming (WCSR) is expected to be used in chemical recuperative cycle of scramjet because of its high chemical heat sink and low coke deposition. Therefore, a numerical model is established and validated based on experiments to improve utilization of chemical heat sink, generated from WCSR at supercritical pressures. The numerical results indicate that a maximal value exists at the axial distribution of chemical heat sink under the combined influence of endothermic and exothermic reactions in WCSR. The chemical heat sink increases to the maximal value, and then decreases after it. The radial chemical heat sink is of layer distribution. According to the fundamental numerical study on influence of key parameters on the WCSR, the results indicate that the maximal value of chemical heat sink has reduced by 15% as operation pressure increases from 3 MPa to 5 MPa, which is distinctly different from that of pyrolysis. As velocity decreases, the maximal value of chemical heat sink moves toward inlet and the total chemical heat decreases. In addition, the chemical heat sink increases with inlet water content, and the maximal value of chemical heat sink has increased by about 50% as inlet water content increases from 5% to 10%.

Investigation of the Properties of Semisynthetic Oils Obtained in the Presence of Dispersed Catalysts Based on Mo and Fe-Co in the Process of Catalytic Steam Cracking of Vacuum Residue

A comparative study of dispersed catalysts obtained in-situ on the based of Mo and Fe-Co in the process of catalytic steam cracking of vacuum residue in the slurry-reactor was conducted (water : vacuum residue = 0,1 : 1 ratio, temperature – 450 °C, pressure – 2,0 MPa, feed rate – 0.1 kg/h). Samples of the semisynthetic oil were obtained and characterized. In the rectification process the gasoline, diesel, oil and residual fractions were allocated. A complex of physicоchemical methods was applied to the analysis of light and dark petroleum products. Based on the obtained data the performance properties of the studied fractions were compared. The relationship between the redistribution of components within the fractions and the catalytic properties of dispersed catalysts was established. The efficiency of using Fe-Co catalysts to produce semisynthetic oil with an increased content of light fractions in the process of catalytic steam cracking of vacuum residue is shown

The Use of Dispersed Catalysts in Catalytic Steam Cracking of Heavy Oil

In this paper the influence of dispersed catalysts obtained in situ based on various metals (Mo, Ni, Fe, Co) has been studied on the yield and properties of liquid products in a slurry-reactorat a temperature of 425 °С and a pressure of 20 MPa. The most active catalytic compositions for the process of catalytic steam cracking of oil (Mo and Mo-Fe) were selected. In the presence of dispersed Mo and Mo-Fe catalysts the samples of the semisynthetic oils were produced. In the rectification process the gasoline, diesel, oil and residual fractions were allocated. The selected fractions were analyzed by physicochemical methods for a wide range of performance in comparison with the initial heavy oil. The efficiency of Mo-Fe catalysts for obtaining semisynthetic oil with an increased content of light fractions (i.b.p. – 360 °С) during the catalytic steam cracking of heavy oil was shown

Effect of La2O3 promotion on a Ni/Al2O3 catalyst for H2 production in the in-line biomass pyrolysis-reforming

The effect of La2O3 addition on a Ni/Al2O3 catalyst has been studied in the biomass pyrolysis and in-line catalytic steam reforming process. The results obtained using homemade catalysts (Ni/Al2O3 and Ni/La2O3-Al2O3) have been compared with those obtained using a commercial Ni reforming catalyst (G90LDP). The pyrolysis step has been performed in a conical spouted bed reactor at 500 °C and the reforming one in a fluidized bed reactor placed in-line at 600 °C, using a space time of 20 gcatalyst min gvolatiles−1 and a steam/biomass ratio of 4. The Ni/La2O3-Al2O3 catalyst had a better performance and higher stability than G90LDP and Ni/Al2O3 catalysts, with conversion and H2 yield being higher than 97 and 90%, respectively, for more than 90 min on stream. Nevertheless, conversion and H2 yield decreased significantly with time on stream due to catalyst deactivation. Thus, the deactivated catalysts have been characterized by N2 adsorption-desorption, X-ray diffraction (XRD), temperature programmed oxidation (TPO), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Coke deposition has been determined to be the main cause of catalyst deactivation, with the structure of the coke being fully amorphous in the three catalysts studied.