Enhancing performance of Ni/La₂O₃ catalyst by Sr-modification for steam reforming of toluene as model compound of biomass tar

Abstract

Steam reforming of biomass tar with toluene as the model compound was studied using Sr-doped Ni/La 2 O 3 catalysts prepared using two methods, i.e. co-impregnation of Sr and Ni on La 2 O 3 support (Ni-Sr/La 2 O 3 catalyst) and sequential impregnation of Sr on Ni/La 2 O 3 catalyst (SNL catalyst), which were then calcined at various temperatures (500, 700, and 900 C). These two types of catalysts are found to possess better catalytic performance than the undoped Ni/La 2 O 3 catalyst at the same calcination temperature due to the presence of Sr, which helps in water adsorption at low steam/carbon (S/C) ratio. Moreover, the catalytic performance for catalysts calcined at various temperatures decreases following this trend: 500 C > 700 C > 900 C due to lower BET surface area and lower surface active metal available for reaction. In addition, it is also observed that the Sr/Ni/La 2 O 3 catalyst has better performance than the Ni-Sr/La 2 O 3 catalyst at the same calcination temperature. Further characterization results suggest that in the Ni-Sr/La 2 O 3 catalyst, the Sr is present between Ni and La 2 O 3 support. On the other hand, Sr in the Sr/Ni/La 2 O 3 catalyst is thought to be located on the surface of Ni/La 2 O 3 due to the preparation method. This study shows that more Sr on the catalyst surface has better catalytic activity and stability in steam reforming of toluene. IntroductionThe need for a renewable alternative of energy sources is increasingly urgent due to the rapid depletion of fossil fuel reserves and the costly price tag of crude oil. The utilization of biomass has been receiving more attention as an abundant and cheap source of renewable energy. Among them, biomass gasication has garnered considerable attention for hydrogen/ synthesis gas production, which can then be used for Fischer Tropsch processes, syntheses of methanol and electricity production in the case of a fuel cell. [1][2][3][4] The main challenge in biomass gasication technology is the removal of tar, which is a mixture of various condensable hydrocarbon compounds containing toluene as the major component, followed by naphthalene. 3 Furthermore, tar can polymerize to form more complex structures and aerosols. Tar can condense on particulate lters, heat exchangers, and engines, resulting in plugging and attrition. This further causes a decrease in efficiency of the process operations and an increase in maintenance and operating costs. Tar removal methods can be classied as primary or secondary. Primary methods include all measures taken in the gasication reactor to prevent tar from being formed in the gasier or to convert it.In secondary methods, pretreatment, either chemical or physical, is performed downstream of the gasier. Both primary and secondary methods require the use of a catalyst.Various metal catalysts have been investigated, such as Ni 5-12 Co, [13][14][15][16][9][10][11][12][16][17][18] and noble metal 19 for the steam reforming of biomass tar using toluene as the model compound. Among those metal catalysts, Ni cataly...

A High‐Performance, Low‐Tortuosity Wood‐Carbon Monolith Reactor

“…[12][13][14] Therefore, it is very important to remove tar for the effective use of biomass gasification products. [20,21] However, the main drawback of Ni-based catalysts is their rapid deactivation due to coking and sintering of Ni metal at high temperature. [15][16][17][18][19] Ni is one of the suitable catalysts for the steam reforming of biomass tar due to its low cost and high tar-destruction activity.…”

“…[15][16][17][18][19] Ni is one of the suitable catalysts for the steam reforming of biomass tar due to its low cost and high tar-destruction activity. [20,21] However, the main drawback of Ni-based catalysts is their rapid deactivation due to coking and sintering of Ni metal at high temperature. [22,23] Porous supports can improve the performance of Ni catalysts due to their increased surface area and improved particle dispersion.…”

Preparation, modification and development of Ni-based catalysts for catalytic reforming of tar produced from biomass gasification

“…They found that the Ni catalyst supported on the pre-calcined Ce-Zr prepared by wet impregnation had smaller crystallite size of Ni, higher surface area and higher Ni dispersion, compared with the in-house calcined Ce-Zr supported Ni catalysts prepared by wet and dry impregnation, as shown in Table 4. Oemar et al [118] prepared two kinds of Sr-doped Ni/La 2 O 3 catalysts for steam reforming of toluene as a model tar compound. Co-impregnation and sequential impregnation methods were used to prepare A Ni-Sr/La 2 O 3 catalysts.…”

Toluene steam reforming over nickel based catalysts

“…Over the years, the catalysts used in the steam reforming of TARs have been based primarily on transition metals. Nickel supported on oxides can be highlighted among these transition metals [30][31][32][33][34][35][36][37][38][39][40][41][42][43]. Specifically, a variety of works have focused on the study of Ni catalysts supported in alumina such as Ni/gamma-Al2O3-SiO2 with different silicon precursors [44], nickel catalysts supported on hexaaluminates [45], Ni-doped γ-Al2O3 [46], Ni/Ce-Al2O3 [47], etc.…”