Ni Catalysts Based on Attapulgite for Hydrogen Production through the Glycerol Steam Reforming Reaction

Abstract

Attapulgite (ATP, a natural clay) was used as carrier to produce a nickel-based catalyst (Ni/ATP) for the work that is presented herein. Its catalytic performance was comparatively assessed with a standard Ni/Al2O3 sample for the glycerol steam reforming (GSR) reaction. It was shown that the ATP support led to lower mean Ni crystallite size, i.e., it increased the dispersion of the active phase, to the easier reduction of NiO and also increased the basicity of the catalytic material. It was also shown that it had a significant effect on the distribution of the gaseous products. Specifically, for the Ni/ATP catalyst, the production of liquid effluents was minimal and subsequently, conversion of glycerol into gaseous products was higher. Importantly, the Ni/ATP favored the conversion into H2 and CO2 to the detriment of CO and CH4. The stability experiments, which were undertaken at a low WGFR, showed that the activity of both catalysts was affected with time as a result of carbon deposition and/or metal particle sintering. An examination of the spent catalysts revealed that the coke deposits consisted of filamentous carbon, a type that is known to encapsulate the active phase with fatal consequences.

Synthesis and Mathematical Modelling of the Preparation Process of Nickel-Alumina Catalysts with Egg-Shell Structures for Syngas Production via Reforming of Clean Model Biogas

“…Moreover, according to the XRD analysis, no reflections belonging to transition aluminas, θ-alumina (25.6 • and 43.3 • ), or alpha-alumina (31.2 • and 36.6 • ) were observed, indicating that alumina transformation was not promoted at the temperature used for calcination [24]. The spinel nickel aluminate phase (NiAl 2 O 4 ) was identified by diffraction peaks at 2θ = 19.0 • , 37.0 • and 59.6 • , for all the calcined catalysts, [75,76]. On the other hand, no diffraction peaks corresponding to the nickel oxide phase (NiO) were identified, which indicates either that these structures are smaller than the typical XRD detection limit or that they are nearly amorphous [24,76,77].…”

Recent Progress in the Steam Reforming of Bio-Oil for Hydrogen Production: A Review of Operating Parameters, Catalytic Systems and Technological Innovations

“…As is well understood, the choice of support has a crucial role on the properties of the catalytic system, as it affects the dispersion of the active phase over the surface of the carrier, the stability shown by the catalytic system through the degree of interaction achieved between metal and support. Moreover, the support can influence the reaction pathway and the deposition of carbon [118]. For the SR of bio-oil in particular, the organic molecules are dissociatively adsorbed on metal sites, whereas H 2 O molecules are adsorbed on the supporting metal oxide surface (e.g., Al 2 O 3 , MgO).…”

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.…”