N-Heptane hydroconversion over sulfated-zirconia-supported molybdenum carbide catalysts

F F Oloye,J A Anderson,A J Mccue

doi:10.1007/s13203-016-0172-z

Abstract

Molybdenum carbide on sulfated zirconia was prepared by impregnation of MoO3 on sulfated zirconia to give a loading of 5 wt% followed by carburisation at 923 K in a mixture of CH4/H2 (4:1). The resulting catalyst was characterised by N2 adsorption–desorption, CO chemisorption, FTIR of pyridine adsorption, XRD, TPR, TGA, Raman and SEM–EDX. This combination of characterisation studies suggests formation of a well-dispersed Mo2C phase over tetragonal zirconia. When employed in the hydroconversion of n-heptane, high temperature and low space velocity lead to substantial cracking. However, under some conditions, an increase in the research octane number (RON) from 0 (n-heptane) to ca. 50 was attained. Between 723 and 873 K, n-heptane is mainly cracked to iso-pentane and ethane. The product distribution as a function of conversion suggests that the reaction did not simply follow a consecutive reaction pathway, but that other parallel routes were involved.

Highlights

Octane number is a measure of resistance of an engine to auto-ignition or premature detonation when exposed to heat and pressure in the combustion chamber of an Surface Chemistry and Catalysis, Materials and Chemical Engineering Group, School of Engineering, University of Aberdeen, Aberdeen AB24 3UE, UK internal-combustion engine [1]
Molybdenum carbide on sulfated zirconia was prepared by impregnation of MoO3 on sulfated zirconia to give a loading of 5 wt% followed by carburisation at 923 K in a mixture of CH4/H2 (4:1)
Solid acid catalysts that operate at low temperature (\423 K) are the current preferred catalysts used in refineries, because they give high activity at low temperature, which favours isomer yield, given the exothermicity of the isomerisation reaction [4, 6, 7]

Summary

Introduction

Octane number is a measure of resistance of an engine to auto-ignition or premature detonation when exposed to heat and pressure in the combustion chamber of an Surface Chemistry and Catalysis, Materials and Chemical Engineering Group, School of Engineering, University of Aberdeen, Aberdeen AB24 3UE, UK internal-combustion engine [1]. The problem of corrosion and waste disposal are the major challenges with this type of catalysts Another example of catalyst that has been widely reported to be active at low temperature is a catalyst based on sulfated zirconia [8,9,10,11,12,13]. This type of catalyst appears susceptible to deactivation which appears to originate from high levels of carbonaceous deposits derived from cracking of higher alkanes, poor resistance to poisons such as water, and sulfate loss at high temperature [6, 14, 15]

Objectives

Results

Discussion

Conclusion