The Synthesis and Evaluation of Up-scalable Molybdenum Based Ultra Dispersed Catalysts: Effect of Temperature on Particl
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The Synthesis and Evaluation of Up-scalable Molybdenum Based Ultra Dispersed Catalysts: Effect of Temperature on Particle Size John Thompson Æ Alejandro Vasquez Æ Josephine M. Hill Æ Pedro Pereira-Almao
Received: 9 August 2007 / Accepted: 11 December 2007 / Published online: 5 March 2008 Ó Springer Science+Business Media, LLC 2008
Abstract Unsupported molybdenum (Mo) micro/nanoparticle size range catalysts have been synthesized via precursor salts dissolved within a water-in-oil emulsion and online injected to a decomposition zone simulating processing conditions. The particles were characterized via DLS, reactivity tests and SEM. The effect of decomposition temperature on particle sizes was studied in both a horizontal reactor and vertical reactor configuration. Keywords Mo catalyst Nanocatalyst synthesis Hydroprocessing Hydrotreating Sub-micron catalyst synthesis Water-in-oil emulsion Nanoparticle
1 Introduction Heavy oils are starting to play a significant role in the world energy market as the demand for transportation fuels increases, and the reserves of conventional oil decrease. These oils are more viscous than conventional oils and also contain a significant amount of impurities including sulfur, nitrogen and metals (such as nickel and vanadium). These impurities deactivate the catalysts used in typical processing operations. Thus, in order to produce and refine heavy oils, more advanced technologies, including more efficient catalysts for hydroprocessing, are required [1]. Molybdenum (Mo) based catalysts have been widely used in the petroleum industry for the hydroprocessing of
J. Thompson A. Vasquez J. M. Hill P. Pereira-Almao (&) Schulich School of Engineering, Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta, Canada T2N 1N4 e-mail: [email protected]
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heavy oil fractions [2]. Typically, commercial hydroprocessing catalysts are supported on alumina and used in a fixed or ebullated bed reactor. These catalysts are prone to deactivation because carbonaceous materials or metals deposit at the mouth of the pores of the alumina, causing pore-mouth plugging [3]. As an alternative to supported catalysts, unsupported catalysts have been developed and in particular UD catalysts are of great interest for the processing of heavy feedstock [4]. These catalysts can be discarded when the proportion of catalyst to product needed is extremely low and when the catalyst remaining with the products no longer has a significant impact on the product specifications or quality. These catalysts can also be recycled depending on the process economics. UD catalysts have particular advantages in the upgrading of heavy oil feedstock due to their greater surface area of accessible active sites leading to an increase in the reactive site-to-mass ratio, thereby allowing large complex molecules (i.e. heavy hydrocarbons) to reach active sites rather than plugging pores as is the case in supported catalysts. The methods that have been used to produce materials of nanomet
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