Catalytic steam reforming of toluene as model tar compound using Ni/coal fly ash catalyst

Abstract

Coal fly ash (CFA), a solid waste from power plants, was selected as the support of Ni-based catalysts used for steam reforming of toluene in a fixedbed reactor. The CFA support was thermally pretreatment first, followed by chemical activation with different treatment time (6 h to 4 days) in 2-mol/L HNO 3 solution. Then, series low-cost catalysts were prepared by wet impregnation. The prepared catalysts were characterized suitably by X-ray diffraction (XRD), Brunauere-Emmette-Teller (BET), temperature programmed reduction (TPR), temperature programmed desorption (TPD), and Raman techniques. According to the catalyst characterization, the chemical pretreatment could improve the support property by adjusting the chemical composition. The Fe-rich Fe-Ni and Ni-Co alloy was formed by H 2 reduction on the Ni/CFA-6h and Co-Ni/CFA-6h catalysts, respectively. In the catalytic steam reforming of toluene, the Ni/CFA-6h had the best catalytic active among all monometallic catalysts, which could be attributed to the existence of Fe 0.94 Ni 0.06 particles, and its performance could be further improved after partly replacing Ni by Co. The Co-Ni/CFA-6h catalyst exhibited the best ability of carbon deposit resistance, implying that its catalytic performance slightly lower than Ni/SiO 2 was due to the too large S BET surface area gap. K E Y W O R D S carbon deposit, catalyst, coal fly ash, steam reforming, toluene 1 | INTRODUCTION Recently, the depletion of fossil fuel is increasingly becoming a global concern. So along with the shortage of fossil fuels, biomass has drawn considerable attention owing to its high availability, low emission, and renewability. 1,2 Of all biomass thermochemical conversion technologies, gasification, in particular, enables the transformation of biomass into syngas, which include hydrogen and carbon monoxide. 3 Syngas can be converted into many kinds of chemical substances through the Fischer-Tropsch method and can be used for power generation. 4-6 However, the formation of tar in the syngas is the primary challenge and urgently facing the gasification process. 7 Biomass tars mainly are largely aromatic hydrocarbons, such as benzene, toluene, and naphthalene, and they constitute condensable fractions of the organic gasification product. 8 The presence of tar in syngas contributes to end-use problems such as blockages and corrosion in downstream filters, fuel line, engine nozzles, and turbines. 9 Therefore, the removal of biomass tar is an urgent problem to be solved at present.

Entrained-Flow Coal Gasification Process Simulation with the Emphasis on Empirical Char Conversion Models Optimization Procedure

“…The volatile matter evolved during the process is assumed to consist of tar, light gases, H 2 O, CO, and CO 2 . The tar molecule was assumed to be a C x H y O z molecule with C 7 as the main component [47,48]. Light gases are considered as an C m H n molecule.…”

Impact of Chemistry–Turbulence Interaction Modeling Approach on the CFD Simulations of Entrained Flow Coal Gasification

“…The volatile matter evolved during devolatilization consists of tar, light gases, H2O, CO, and CO2. The tar molecule was assumed to be a CxHyOz molecule with C7 as the main component [40,41]. Light gases are treated as a CmHn molecule.…”

“…The simplest approach is to consider infinitely fast chemistry which stems from the observation that during high-temperature combustion most of the produced species The volatile matter evolved during devolatilization consists of tar, light gases, H 2 O, CO, and CO 2 . The tar molecule was assumed to be a C x H y O z molecule with C 7 as the main component [40,41]. Light gases are treated as a C m H n molecule.…”

Activity and Stability of Different Fe Loaded Primary Catalysts for Tar Elimination

“…However, one of the main shortcomings of biomass gasification lies in the presence of tars in the product stream, which leads to fouling/clogging and corrosion of downstream equipment [3][4][5]. Hence, in order to minimize the amount of tar and improve the syngas composition, its catalytic conversion is one of most promising routes [6,7]. This process involves the oxidation of the tar components using steam to produce a syngas richer in H 2 and, furthermore, the presence of the catalyst allows a more effective tar removal at lower temperatures than those in the non-catalytic tar conversion [8].…”

“…The selection of temperature and catalyst determines the extent of these reactions and the selectivity towards the different products [7,[15][16][17][18].…”