Toluene steam reforming over nickel based catalysts

Abstract

Steam reforming of toluene (SRT) has been studied initially in eight nickel-based catalysts where nickel (10 wt.%) was incorporated in different supports (olivine, Al2O3, MgO, LDH, ZrO2, CeO2 and natural sepiolite) by the incipient wetness impregnation method. Among them, nickel catalyst based on sepiolite exhibited a promising catalytic performance, with a high conversion of toluene (16%), high selectivity to hydrogen (68.4%) and low production of undesired by-products (CO, CH4, ethylene and benzene) at low temperature (500 ºC). On the other hand, the incorporation of Ni in the sepiolitic material by precipitation (PP) has been considered as alternative method to the incipient wetness impregnation method (IWI). PP method allowed to prepare a Ni-based catalyst with a very high activity (conversion of toluene ~100%), high selectivity to hydrogen (73%) and lower production of undesirable by-products (5% CO, 2% CH4 and 0% C6H6) at 575 ºC. In addition, catalytic deactivation due to coke deposition and nickel sinterization was clearly lower for the catalyst synthesized by PP. Characterization by different physicochemical techniques (XRD, TEM, BET surface area, ICP-OES, TPR and EA) showed that PP method allowed to obtain a sepiolite-based catalyst containing Ni with larger external surface area and smaller, highly dispersed and easily reducible Ni metal particles. The results here discussed show that the Ni incorporation method has a clear influence in the preparation of nickel catalyst supported on sepiolite with improved catalytic performance in the steam reforming of toluene.

Effects of Sn doping on the manufacturing, performance and carbon deposition of Ni/ScSZ cells in solid oxide fuel cells

“…Although Ni is an excellent catalyst for both electrochemical oxidation reaction and reforming reaction in producing hydrogen and syngas (H2 and CO) [44][45][46][47][48], Ni also prone to carbon deposition. Hence, Ni-free anode with alternative metal [6,17,49] and perovskites material [50,51] On the other hand, Singh et al [42] and Lay et al [61] reported no significant performance difference and higher amounts of carbon observed on the Sn doped cells compared to the undoped cells with either low steam to carbon ratio.…”

Investigation of support effects during ethanol steam reforming over a Ni/sepiolite catalyst

“…Specifically, the peak at 430 °C corresponds to the reduction of NiO interacting with silica, 26,32,33 the peak at 620 °C is associated with the reduction of NiO–MgO on the surface and the peak at 750 °C relates to the reduction of NiO–MgO in the bulk. 34,35 Regarding the Ni/sepiolite catalyst treated at higher temperature (550 °C), a minor impact on the reduction temperatures is observed with similar peaks appearing at 450 °C, 630 °C and 740 °C. Based on the obtained TPR results and considering that before experimental testing the catalyst was reduced at 500 °C, the degree of Ni reduction was estimated to be 49% and 51% for the sample thermally treated at 500 °C and 550 °C, respectively.…”

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

“…moles of H 2 in the product gas maximum moles of H 2 allowed by stoichiometry (13) The maximum number of H 2 moles allowed by stoichiometry was calculated by considering toluene reforming reaction and that of WGS. Thus, H 2 potential is defined based on the maximum number of H 2 moles obtained when toluene is fully reformed to CO 2 and H 2 .…”

“…Tar model compounds have been widely used in order to ascertain the catalyst performance and determine suitable operating conditions. In this work, toluene was selected as a tar model compound because it is a stable aromatic structure, especially at relatively low temperatures, apart from being one of the major tar species in the biomass gasification [10][11][12][13][14].…”

“…From a catalytic point of view, nickel is known to be the most interesting metal phase for reforming applications [30]. Ni-based catalysts have been widely applied in the steam reforming of biomass tars due to both their high activity for breaking C-C and O-H bonds and performance in terms of H 2 production [7,12,13,[31][32][33][34][35]. However, their main drawbacks are related to their rapid deactivation, mechanical fragility and high cost compared to natural minerals or alumina [36].…”