(127f) Ni/Cerium-Titanium Oxide Catalyst for Dry Reforming of Methane

Sachin U. Nandanwar,^a,b Yunkai Zou,^a Joseph H. Holles,^b Jing Zhou,^a Samantha Hulett^c, Michael Cuddy^c

^aDepartment of Chemistry, University of Wyoming, Laramie, WY 82071, and Email address: jzhou2@uwyo.edu

^bDepartment of Chemical Engineering, University of Wyoming, Laramie, WY 82071, and Email address: jholles@uwyo.edu

^cDepartment of Chemistry, Northwest College Wyoming, Powell, WY 82435, and Email address:

Michael.Cuddy@nwc.edu

Abstract

The world energy demand is continuously increasing due to rapid industrialization and increasing population, coinciding with the depletion of nonrenewable traditional fossil fuels. Therefore, it is essential to find an alternative, clean energy source to fulfill energy demand of modern society. Dry reforming of methane is one of several potential reactions to produce energy from greenhouse gases. This reaction involves the reforming of methane in the presence of CO₂ over a heterogeneous catalyst to produce syngas (H₂ and CO), which is mostly use as precursor in chemical industry or converted to liquid fuels. However, this reaction required high temperature to break the C-H bond due to endothermic nature. The heterogeneous catalyst plays a significant role in this reaction to reduce the energy barrier and helps to run the reaction successfully. Up to now, various heterogeneous catalysts have been investigated for dry reforming of methane such as Pt/CeO₂-ZrO₂, Ni/g-Al₂O₃,Ni/TiO₂, Ni/ceria–zirconia and Ni/CeO₂. Ni-based catalysts are the primary choice because these are coke resistance, stable long term, easily available, economical and show promising results. Nevertheless, the current catalysts are deactivated during the reaction by depositing coke residue on active sides, and sintering of Ni nanoparticles at high reaction temperature. Therefore, it is basic need to develop the effective support to make Ni nanoparticles stable to withstand at high reaction temperature and enhance the activity of the catalyst by supplying the extra amount of oxygen during reaction. The designed catalyst should be effective in diverse ways: CH₄ activation, CO₂activation, coke resistance, high yield of products and economical to commercialization. Therefore, the cerium-titanium oxide was developed to change the textural feature of cerium oxide, which improved the physical properties of materials such as robustness, thermal resistance and exchange of oxygen.

A Ni-supported cerium-titanium oxide catalyst was synthesized by the sol-gel technique. Initially, cerium-titanium, Ce_1-xTi_xO_2-d (x – 0.1, 0.2, 0.3 and 0.5) support was synthesized by two precursors, cerium (III) nitrate hexahydrate and titanium (IV) isopropoxide. Citric acid was used as a complex agent for formation of loosely agglomerate nanosized materials. Then, Ni was deposited onto the support by sol-gel method. Nickel (II) nitrate hexahydrate was used as source of nickel. The prepared catalyst was characterized by X-ray diffraction, Scanning Electron Microscopy-Energy Dispersive Spectroscopy and BET surface area. XRD analysis shows the formation of Ce_1-xTi_xO_2-d solid materials for all Ce:Ti ratio. The highest surface area of 2 wt% Ni-support Ce_0.7Ti_0.3O_2-d catalyst was ~ 26 m² g^-1. The catalytic performance of developed catalyst was investigated for dry reforming of methane by varying different parameters such as effect of different supports and reaction temperatures. The 2wt% Ni/Ce_0.7Ti_0.3O_2-d catalyst shows the remarkable result for dry reforming of methane. The 68% CH₄ conversion and 47% H₂ yield were obtained at 600°C. The result of our study shows the developed catalyst improved CH₄ conversion, hydrogen yield and coke resistance during the reaction.