Synthesis of NiO/Y2O3/ZrO2 Catalysts Prepared by One-Step Polymerization Method and Their Use in the Syngas Production from Methane

Yvan J O Asencios,Elisabete M Assaf

doi:10.1155/2018/9487486

Abstract

In this work, the production of Syngas (H2/CO) from oxidative reforming of methane (ORM) and partial oxidation of methane (POM) over NiO/Y2O3/ZrO2 catalysts was studied. The nickel concentration was varied (ranging from 0 to 40 wt.%) aiming to optimize the performance in ORM and POM reactions; these reactions were carried out at 750°C and 1 atm for 6 hours. The catalysts were prepared by the one-step polymerization method (OSP) and characterized by different techniques. This method led to production of materials of smaller crystallite size than others of similar composition prepared under other methods; the catalysts presented good nickel dispersion, well-defined crystalline structure, and well-defined geometrical morphology. Additionally, the OSP method was advantageous because it was carried out in a single calcination step. The catalyst containing 20% wt. of nickel (20Ni20YZ sample) showed the highest methane conversion, high selectivity to H2 and CO, low carbon deposition rates, and, curiously, the best geometric morphology. The results of this paper also demonstrated that the nickel concentration in the mixture strongly influenced the morphology of the catalysts; therefore, the morphology also influenced the catalytic performances during the Syngas production reactions.

Highlights

Methane is found mainly in biogas, natural gas, and shale gas
It is known that catalysts based on noble metals corresponding to the Group VIIIB are good catalysts for reforming methane (e.g., Pt, Rh, Pd, and Ru), demonstrating high selectivity for hydrogen, high methane conversion, and low carbon deposition rates. e catalysts based on nonnoble metals of Group VIIIB (Ni, Co, and Fe) have shown catalytic activity in methane reforming reactions, to that of noble metals based catalysts, and they are low cost; nonnoble metals result in high carbon deposition rates [6, 8, 9]
Conclusions e production of Syngas from methane through the partial oxidation of methane (POM) and ORM over the catalysts rose as the Ni content increased, and the optimal nickel content in the NiO/Y2O3/ZrO2 mixture prepared under the one-step polymerization method (OSP) method was 20% wt

Summary

Introduction

Methane is found mainly in biogas, natural gas, and shale gas. Biogas is a renewable alternative source of methane and is considered a first-generation biofuel. e production of the biogas occurs in the absence of oxygen where anaerobic bacteria break down the organic matter, producing methane and carbon dioxide as major products, and other gaseous by-products such as H2S, NH3, and H2, in smaller amounts [1, 2].Syngas (synthesis gas, a mixture of H2/CO) is a raw material of high value which is used as the starting material in the production of synthetic fuels such as di-methyl ether (DME), methanol, and liquid hydrocarbons (by the Fischer–Tropsch process). Carbon dioxide and methane are the two principal components of biogas, and the main greenhouse gases, so its transformation into Syngas may have very beneficial results. E catalysts based on nonnoble metals of Group VIIIB (Ni, Co, and Fe) have shown catalytic activity in methane reforming reactions, to that of noble metals based catalysts, and they are low cost; nonnoble metals result in high carbon deposition rates [6, 8, 9]. E actual Syngas production by industry (for hydrogen generation) is based on the steam reforming of methane (SRM, reaction (4)), which uses a nickel catalyst supported on alumina; nickel catalysts present problems due to carbon deposits which deactivate the catalyst (covering the active metallic sites) and its accumulation increases the reactor pressure, leading to explosion hazards. Many efforts have been directed to decrease carbon deposits [10, 11]

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