Gas Catalyst Research Articles

Promotional effects of Ce on Ni[sbnd]Ce/γAl2O3 for enhancement of H2 in hydrothermal gasification of biomass

This communication presents promotional effects of Ce on a NiCe/γ-Al2O3 catalyst for biomass gasification in hydrothermal reaction conditions. The catalyst samples were prepared by an incipient wetness technique using a successive metal loading approach. The TPR/TPO results showed that the presence of Ce minimized metal support interaction and improved the reducibility and thermal stability of the catalyst. The XRD analysis of fresh and reduced (after 10 repeated TPR/TPO cycles) catalyst samples showed unchanged crystal structures of the nickel particles indicating stable properties of the NiCe/γAl2O3 catalyst. The hydrothermal biomass gasification experiments were conducted using glucose as a biomass surrogate at various reaction temperature (425–525 °C) and time (5–35 min), while the pressure was maintained at 25.5 MPa. It was observed that the addition of Ce influenced the catalyst surface creating more active nickel sites for steam reforming methane reaction. Ce also increased the activity of Ni/γAl2O3 catalysts in terms of hydrogen production by promoting the water gas shift reaction and suppressing the methanation reaction of carbon dioxide.

A protonic ceramic membrane reactor for the production of hydrogen from coal steam gasification

In the present work, the feasibility of producing and simultaneously separating hydrogen from coal steam gasification (CSG) in a protonic ceramic membrane reactor (PCMR) is demonstrated. A Cu/BZCY81/Ni-BZCY72 tubular cell was employed as the PCMR for the studies. Saturated steam was fed over a mixture of powdered carbon black and K2CO3 gasification catalyst, which was in contact with the Cu anode. At 600–700 °C, the electrochemical separation of generated H2 from the gasification chamber (anode) was found to enhance the reaction rate to H2 and CO2 by up to 60%. This novel approach to the steam gasification of carbon holds promise for the production of high purity H2 from coal- or biomass-based electrochemical processes at much lower operation temperatures, compared to the conventional thermochemical methods.

Catalytic gasification characteristics of cellulose, hemicellulose and lignin

Abstract In this paper, catalytic gasification experiments of three major biomass components (cellulose, hemicellulose, and lignin), straw, and pine were performed with dolomite and Na2CO3 as catalysts on a small-scale entrained-flow gasifier. We focused on the differences of catalytic gasification characteristics among three major biomass components. Sodium carbonate and dolomite largely positively promoted hemicellulose gasification, significantly improved the gasification efficiency, calorific value of gas, and carbon conversion, and significantly reduced the tar yield. Sodium carbonate showed the optimal catalytic effect. Dolomite positively catalyzed the gasification of cellulose, hemicellulose, lignin, straw, and pine. Sodium carbonate significantly catalyzed the gasification of hemicellulose, but it inhibited the gasification of cellulose, lignin, straw, and pine. Sodium carbonate is suitable to catalyze the gasification of biomass with a high content of hemicellulose. The influences of different catalysts on the catalytic gasification characteristics of cellulose, hemicellulose and lignin were different. Therefore, the selection of biomass gasification catalyst should be based on the components and properties of biomass.

Effect of limestone catalyst on co-gasification of coconut fronds and wood chips

Biomass energy via gasification is an attractive substitute of fossil fuels. The distribution of biomass on the earth is scattered, so transportation and collection of biomass complicates the supply of biomass especially when the gasification rely on one type of biomass. Therefore, cogasification of different biomass is proposed as a potential solution for interruption-free gasification. Beside, unwanted by-products such as tar that cause blockage in downstream equipment can be minimized through the use of catalyst in gasification to accelerate tar reforming process. In this study, catalytic co-gasification of blended feedstock of 70% wood chips and 30% coconut fronds was carried out in a downdraft gasifier using limestone as primary catalyst. The effects of catalyst loading (0%, 30%, 50%, and 70% w/w) on syngas composition, gas yield, carbon conversion efficiency and heating value of syngas were investigated. The results showed that at 50% biomass to catalyst ratio, maximum H2 content of 11.39%, CO of 17.88%, carbon conversion efficiency of 69.49%, gas yield of 1.68 Nm3/kg and higher heating value of syngas 5.11 MJ/Nm3 were achieved. Higher catalyst loading (70%) blocked the air passage, which caused poor gasification. No more than 50% catalyst suggested for stable co-gasification operation.

Rapid screening of gaseous catalysts in methane activation using ICP-QQQ-MS

A novel platform for rapid screening of gaseous catalysts in methane activation using ICP-QQQ-MS was developed.

Gasification of n-C7 asphaltenes using Ni-based catalysts

ABSTRACTCatalytic performance of two Ni-based catalysts (Ni-Pt and Ni-Pt-Al) in steam gasification of n-C7 asphaltenes (C7A) was examined. The influence of the catalysts composition and operating parameters (residence time and temperature) on hydrogen yield and char conversion was studied showing a high hydrogen production and a low char formation compared to Ni-Pt alone. From the result of the gasification of rice C7A over Ni-Pt/Ni-Pt-Al catalysts, it is found that the raising the Pt/Ni ratio increases the quantity of generated hydrogen, but this increase is greater in the presence of the Ni-Pt-Al catalyst because the tar cracking process improves with increased collisions and also with improved activation energies of the reactions in the presence of Al.

Micropore structure stabilization in organosilica membranes by gaseous catalyst post-treatment

A post-treatment involving repeated exposure to gaseous HCl alternated with heating is demonstrated to strongly accelerate the recently reported structural evolution in organically bridged silica networks. Films, powders and membranes derived from 1,2-bis(triethoxysilyl)ethane were exposed to in-situ synthesized HCl gas, alternated with heat treatments at 150–300°C in air or N2. The film thickness, network condensation, chemical integrity and micropore structure were monitored with X-ray reflectivity, 29Si direct-excitation magic-angle spinning nuclear magnetic resonance, Fourier-transform infrared spectroscopy and gas permeation. Treatment with HCl was found to predominantly catalyze hydrolysis, enabling network optimization via iterative bond breakage and reformation. Network shrinkage, widening or opening of the smallest pores and densification of the overall pore structure were accelerated while the ethylene bridges remained intact. The achieved acceleration of material evolution makes iterative hydrolysis and condensation a promising approach for increasing the long-term micropore stability of molecular sieving membranes.

Metal Oxide Nanoparticles Supported on Macro-Mesoporous Aluminosilicates for Catalytic Steam Gasification of Heavy Oil Fractions for On-Site Upgrading

Catalytic steam gasification of extra-heavy oil (EHO) fractions was studied using functionalized aluminosilicates, with NiO, MoO3, and/or CoO nanoparticles with the aim of evaluating the synergistic effect between active phase and the support in heavy oil on-site upgrading. Catalysts were characterized by chemical composition through X-ray Fluorescence, surface area, and pore size distribution through N2 adsorption/desorption, catalyst acidity by temperature programmed desorption (TPD), and metal dispersion by pulse H2 chemisorption. Batch adsorption experiments and catalytic steam gasification of adsorbed heavy fractions was carried out by thermogravimetric analysis and were performed with heavy oil model solutions of asphaltenes and resins (R–A) in toluene. Effective activation energy estimation was used to determine the catalytic effect of the catalyst in steam gasification of Colombian EHO. Additionally, R–A decomposition under inert atmosphere was conducted for the evaluation of oil components reactions with active phases and steam atmosphere. The presence of a bimetallic active phase Inc.reases the decomposition of the heavy compounds at low temperature by an increase in the aliphatic chains decomposition and the dissociation of heteroatoms bonds. Also, coke formation after steam gasification process is reduced by the application of the bimetallic catalyst yielding a conversion greater than 93%.

Investigation of Na2SO4 removal from a supercritical aqueous solution in a dip-tube salt separator

Solar-driven hydrothermal gasification is an efficient process to exploit the energetic potential of biomass containing high amounts of water. This process requires effective removal of the type-2 salts from the feedstock as their precipitates can plug the equipment and poison the gasification catalyst. This work investigates the effect of the axial temperature profile on type-2 salt deposition in a dip-tube salt separator operated with an aqueous Na2SO4 solution as model feed and presents a method for online detection and monitoring of the growth of the deposits. Our results suggest that preventing the salt deposition at the wall of the separator by controlling the axial temperature profile is not possible. The online monitoring of the salt deposition is thus indispensable for scheduling the timely removal of the salt deposits.

Structured catalytic reactor for soot abatement in a reducing atmosphere

Nanostructured Li-delafossite based catalysts were prepared via solution combustion synthesis (SCS) method and investigated under realistic conditions as catalysts for the carbon gasification in a reducing environment. LiFeO2 catalyst was selected as the most promising candidate for the soot gasification catalyst on a soot trap application close coupled to a biogas autothermal reforming (ATR) reactor for syngas post-treatment process. LiFeO2 was coated on a wall-flow monolith filter (15/20μm mean pore size and 46% porosity) via solution combustion deposition (SCD) method and the coated filters' performance was evaluated during the soot particles loading. The pressure drop across the filters was very low (<8mbar), showing that the method of coating on the filters was successfully applied.

Preparation and characterization of nickel loaded on resin char as tar reforming catalyst for biomass gasification

A novel porous carbon catalyst was prepared by carbonization of D151 resin exchanged with nickel ion (Ni/RC). TEM images and XRD patterns manifest that nickel crystallite size (NCS) relies greatly on solution pH value and carbonization temperature. The as-prepared Ni/RC in pH 11 at 650°C achieved the maximal specific surface area of 213m2/g and metallic nickel particles are highly dispersed with a NCS of 5.7nm. Ni/RC exhibited higher activity for corncob tar reforming than commercial Ni/Al2O3 and produced a gas yield of 46.8mmol/g at 650°C. The nickel particles growth above 650°C causes the decline in catalytic activity of Ni/RC. In the presence of steam, a high tar-free gas of 84.5mmol/g was obtained at 650°C. This study sheds light on the possibility of Ni/RC as a promising candidate for H2-rich gas production from biomass under mild conditions.

Nickelocene-Precursor-Facilitated Fast Growth of Graphene/h-BN Vertical Heterostructures and Its Applications in OLEDs.

The direct growth of high-quality, large-area, uniform, vertically stacked Gr/h-BN heterostructures is of vital importance for applications in electronics and optoelectronics. However, the main challenge lies in the catalytically inert nature of the hexagonal boron nitride (h-BN) substrates, which usually afford a rather low decomposition rate of carbon precursors, and thus relatively low growth rate of graphene. Herein, a nickelocene-precursor-facilitated route is developed for the fast growth of Gr/h-BN vertical heterostructures on Cu foils, which shows much improved synthesis efficiency (8-10 times faster) and crystalline quality of graphene (large single-crystalline domain up to ≈20 µm). The key advantage of our synthetic route is the utilization of nickel atoms that are decomposed from nickelocene molecules as the gaseous catalyst, which can decrease the energy barrier for graphene growth and facilitate the decomposition of carbon sources, according to our density functional theory calculations. The high-quality Gr/h-BN stacks are proved to be perfect anode/protecting layers for high-performance organic light-emitting diode devices. In this regard, this work offers a brand-new route for the fast growth of Gr/h-BN heterostructures with practical scalability and high crystalline quality, thus should propel its wide applications in transparent electrodes, high-performance electronic devices, and energy harvesting/transition directions.

Interaction of Potassium and Calcium in the Catalytic Gasification of Biosolids and Switchgrass

Catalytic gasification is a method of converting biosolids, the solids created during wastewater treatment, into a valuable gaseous stream. One of the challenges with this process is that the components in the ash of the biosolids can interact with the gasification catalyst(s)—in particular, calcium and potassium. In this study, the behaviors of different combinations of switchgrass (the source of potassium), biosolids, ash-free carbon black, and mixtures of each feed with added calcium and/or potassium were observed with a thermogravimetric analysis unit. The results were consistent with calcium preferentially reacting with components in the ash, preventing the deactivation of potassium. Any additional calcium available may form bimetallic compounds with the potassium, but this interaction did not increase the rate of reaction. Modeling was performed using the random pore model and extended random pore model, with the appropriate model chosen for each mixture. The extended random pore model was better su...

Enhancement of glucose gasification by Ni/La2O3-Al2O3 towards the thermodynamic extremum at supercritical water conditions

This communication presents the promotional effects of La on Ni/La-Al2O3 catalyst for biomass gasification in supercritical water using glucose as a biomass surrogate. The experimental findings were also compared with the product compositions predicted by the thermodynamic model. In modeling, the equations of state (EoS) by Peng–Robinson, as well as by Duan, were separately used to derive the residual Gibbs' free energy and compressibility factor, Z. Results, obtained by both EoS showed close agreement. The accuracy of our calculation was checked by comparing the compressibility factor, Z of the gaseous products, with those obtained from Aspen-HYSYS. In all cases considered, the percentage error in Z was less than 10%. Moreover, we have found that water to glucose (W/G) ratio affects the syngas composition. For example, at 600 °C and 25 MPa, an increase in W/G ratio from 6 to 9 led to an increase in H2/CO ratio from ∼3.2 to ∼4.7. On the other hand, operating pressure has little effect on syngas composition. This finding could be useful in the design and optimization of supercritical water gasification (SCWG) plants. Finally, we also observed that lanthanum helped to drive the hydrogen yield towards the thermodynamic extremum, while at the same time scavenging CO2 and coke, and retarding the methanation reaction.

3-15 木質系バイオマスのガス化で生じるタールの分解触媒の開発((4)ガス化4,Session 3 バイオマス等)

3-15 木質系バイオマスのガス化で生じるタールの分解触媒の開発((4)ガス化4,Session 3 バイオマス等)

P-13 Utilization of Biomass Ash as Catalyst for Low Temperature Coal Gasification

P-13 Utilization of Biomass Ash as Catalyst for Low Temperature Coal Gasification

25 バイオマス低温ガス化触媒Ni-MgO/Al_2O_3の炭素析出による失活挙動に関する研究(ガス化・燃焼(1))

25 バイオマス低温ガス化触媒Ni-MgO/Al_2O_3の炭素析出による失活挙動に関する研究(ガス化・燃焼(1))

3-1-2 ガス化ガス中タールへの耐性を持つ燃料電池用機能性電極触媒に関する研究(Session 3-1 ガス化I)

3-1-2 ガス化ガス中タールへの耐性を持つ燃料電池用機能性電極触媒に関する研究(Session 3-1 ガス化I)

3-2-4 バイオマス流動接触分解ガス化のための粘土触媒の評価

3-2-4 バイオマス流動接触分解ガス化のための粘土触媒の評価

Noble-metal-free bimetallic alloy nanoparticle-catalytic gasification of phenol in supercritical water

The exploration of non-noble-metal catalysts for high efficiency gasification of biomass in supercritical water (SCW) is of great significance for the sustainable development. A series of Ni–M (M=Co or Zn) bimetallic nanoparticles supported on graphitized carbon black were synthesized and examined as catalysts for gasification of phenol in SCW. It was found that a nearly complete gasification of phenol can be achieved even at a low temperature of 450°C with the bimetallic nanoparticles catalysts. Kinetic study indicated the activation energy for phenol gasification were 20.4±2.6 and 43.6±2.6kJ/mol for Ni20Zn15 and Ni20Co15 catalyst, respectively. XRD, XPS and TEM were further performed to characterize the catalysts and the results showed the formation of NiCo and NiZn alloy phase. Catalyst recycling experiments were also conducted to evaluate the stability of the catalysts. The characterization of used catalysts suggest that the severe agglomeration of nanoparticles leads to the decrease in catalytic activity.