A series of ceria-zirconia mixed oxide supports with nominal composition "Ce 0.6 Zr 0.4 O 2 " were synthesized by two different routes, namely, a surfactant-assisted route and a coprecipitation route. Among the supports obtained by the surfactant-assisted route, different surfactant/metal molar ratios (namely, 1.25, 0.8, and 0.5) were employed to study the influence of the surfactant amount on the catalyst performance. A nominal 5 wt % Ni was impregnated on the supports by a wet impregnation method. These catalysts were evaluated for CO 2 reforming of CH 4 in both the presence and absence of steam. The textural, structural, and physicochemical characteristics of the catalysts were thoroughly investigated with the help of various bulk and surface characterization techniques. The activity results indicate the superior nature of the catalysts obtained by the surfactant-assisted route over the one obtained by coprecipitation. Also, within the limits of the surfactant ratios used, the amount of surfactant employed during the course of support preparation seems to affect the activity, with catalysts prepared with the higher surfactant/metal molar ratio exhibiting better activity and enhanced stability. Structure-activity relationships (SARs) were formulated for some of the characteristics in order to explain the marked difference in activity between the catalysts obtained by the surfactant-assisted and coprecipitation methods and between the catalysts prepared by the surfactant-assisted route but with different surfactant/metal molar ratios. The SARs helped to identify that high oxygen storage capacity, high surface area, high reducibility, higher nickel surface area, better nickel dispersion, and higher surface nickel content are necessary for good performance in the CO 2 reforming of CH 4 . On the whole, catalysts obtained by the surfactant-assisted route exhibit a reasonably good performance in the CO 2 reforming reaction but were prone to deactivation in the presence of steam. The inherent hydrophilic nature of the ceria-zirconia support is the main cause for the apparent deactivation in the presence of steam.

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In this report, the adsorption of CO 2 on metal organic frameworks (MOFs) is comprehensively reviewed. In Section 1, the problems caused by greenhouse gas emissions are addressed, and different technologies used in CO 2 capture are briefly introduced. The aim of this chapter is to provide a comprehensive overview of CO 2 adsorption on solid materials with special focus on an emerging class of materials called metal organic frameworks owing to their unique characteristics comprising extraordinary surface areas, high porosity, and the readiness for systematic tailoring of their porous structure. Recent literature on CO 2 capture using MOFs is reviewed, and the assessment of CO 2 uptake, selectivity, and heat of adsorption of different MOFs is summarized, particularly the performance at low pressures which is relevant to post-combustion capture applications. Different strategies employed to improve the performance of MOFs are summarized along with major challenges facing the application of MOFs in CO 2 capture. The last part of this chapter is dedicated to current trends and issues, and new technologies needed to be addressed before MOFs can be used in commercial scales.

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Abstract:Over the past few years, great attention is paid to syngas production processes from different resources especially from abundant sources, such as methane. This review of the literature is intended for syngas production from methane through the dry reforming (DRM) and the steam reforming of methane (SRM). The catalyst development for DRM and SRM represents the key factor to realize a commercial application through the utilization of more efficient catalytic systems. Due to the enormous amount of published literature in this field, the current work is mainly dedicated to the most recent achievements in the metal-oxide catalyst development for DRM and SRM in the past five years. Ni-based supported catalysts are considered the most widely used catalysts for DRM and SRM, which are commercially available; hence, this review has focused on the recent advancements achieved in Ni catalysts with special focus on the various attempts to address the catalyst deactivation challenge in both DRM and SRM applications. Furthermore, other catalytic systems, including Co-based catalysts, noble metals (Pt, Rh, Ru, and Ir), and bimetallic systems have been included in this literature review to understand the observed improvements in the catalytic activities and coke suppression property of these catalysts.

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