Ingeniero Indusrtial

Synthesis Gas Production by Methane Partial Oxidation on Ni/Fe3O4‐Ce0.75Zr0.25O2 Catalysts: Kinetic Study

M. I. Sosa Vazquez, J. Salinas Gutierrez, D. Delgado Vigil, V. Collins-Martinez and A. Lopez Ortiz*

Departamento de Materiales Nanoestructurados, Centro de Investigación en Materiales Avanzados, S. C. Miguel de Cervantes 120, Chihuahua, Chih., México 31109. Received: October 30, 2010,Accepted: January 20, 2011, Available online: April 06, 2011 Abstract: Fe3O4-Ce0.75Zr0.25O2 (FeCZ) is an oxygen carrier material aimed to produce syngas through methane partial oxidation in absence of oxygen gas feed. The objective of the present research is to study the catalytic effect of Ni on FeCZ using an evaluation of the global kinetics (activation energy, reaction rate, order andconstant) of its reaction with methane for syngas production. FeCZ and 0.05NiFeCZ (Ni/Fe = 0.05 molar ratio) were synthesized through co-precipitation of their precursor nitrate salts, while 2NiFeCZ was prepared by impregnation of FeCZ with a nickel nitrate solution to obtain a 2 %W Ni material. Samples were calcined at 950°C during 4 hours in air. Kinetic study of oxygen carriers (FeCZ, 0.05NiFeCZ and2NiFeCZ) reduction with methane was followed through thermogravimetric analysis (TGA) at 5, 7.5 and 10% CH4/Ar and 600, 650 and 700°C. Initial reaction rate was obtained from the slope of the linear region of the weight change signal as a function of time. Results indicate a first order global reaction rate for all materials. Activation energies for samples FeCZ, 0.05NiFeCZ and 2NiFeCZ were 52.2,39.5 and 28.3 Kcal/mol, respectively. Thus, reflecting the catalytic effect of Ni over the FeCZ global reaction rate.

Keywords: Syngas production, methane partial oxidation, oxygen carrier, kinetic study

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1. INTRODUCTION

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*To whom correspondence should be addressed: Email: alejandro.lopez@cimav.edu.mx Phone: +52-614-439-4815; Fax: +52-614-439-1130

Hydrogen, as an energycarrier, has been considered to be an environmentally acceptable option to face the global warming problem that today harms the planet, because during its use does not involve the production of greenhouse gases (CO2). Nowadays, world’s demand for hydrogen is high (approximately 70 million metric tons per year) with industrial applications such as: oil refining, metallurgy, food and electronicindustries among others [1]. Recently, new hydrogen applications have emerged. Among those are fuel cells, which employ hydrogen and oxygen to produce electric energy at higher efficiencies than actual internal combustion engines. With equal importance as hydrogen is the mixture of carbon monoxide and hydrogen (CO +H2), commonly known as synthesis gas or “syngas”, which today is used as a raw materialfor many industrial applications. Furthermore, this mixture is also used to produce hydrogen through the water gas shift reaction process

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(WGS). The conversion of methane to syngas is a crucial step in the use of natural gas towards the production of hydrogen. Moreover, this syngas mixture is a fundamental raw material for the Fischer Tropsch (FT) process, where isconverted to liquid hydrocarbons to produce several synthetic substitutes of petroleum, such as: lube oils, and all kinds of liquid fuels [2]. The use of syngas through the FT process (for the production of liquid fuels) combined with a growing demand of a vast number of chemicals derived from this process, have converted this mixture in an strategic factor for nations with growing economies facing thecontinuous increase in oil prices during the last decade [3]. To supply this growing demand for syngas and hydrogen there has been a growing interest in the scientific community towards research focused in the reduction of operating costs and increasing efficiencies in the related processes. A strategy that has been identified as potentially effective is the introduction of modifications to the...