%0 Journal Article
%T Novel Ni-Co-Mo-K Catalysts Supported on Multiwalled Carbon Nanotubes for Higher Alcohols Synthesis
%A Venkateswara Rao Surisetty
%A Janusz Kozinski
%A Ajay Kumar Dalai
%J Journal of Catalysts
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/942145
%X Alkali-promoted Ni-Co-Mo catalysts supported on multiwalled carbon nanotubes (MWCNTs) were prepared using 9£¿wt% K, 4.5£¿wt% Co, and 15£¿wt% Mo, whereas Ni content was varied from 0 to 6£¿wt%. The catalysts were extensively characterized and studied for higher alcohols synthesis from synthesis gas. Alkali-promoted trimetallic catalyst with 3£¿wt% Ni showed the highest total alcohols yield of 0.284£¿gm/(gm of cat./h), ethanol selectivity of 20%, and higher alcohols selectivity of 32% at 330¡ãC and 9.0£¿MPa using gas hourly space velocity (GHSV) of 3.8£¿m3 (STP)/kg of catalyst/h and H2 to CO molar ratio of 1.25. 1. Introduction Ethanol has been used as an additive for reformulated gasoline as unleaded gasoline has become the standard, and short ether compounds (MTBE, ETBE, etc.) have been banned as gasoline octane continues to improve in North America [1]. The catalytic conversion of syngas to ethanol, and other higher alcohols, is generally recognized as an interesting route for the production of clean fuels and petrochemical feedstocks from coal, natural gas, and hydrocarbon wastes via gasification [2]. The catalysts for higher alcohol synthesis (HAS) are divided into two main groups based on the product distribution [3]. Alkali-doped high-temperature ZnCrO-based and low-temperature Cu-based catalysts produce mainly methanol and higher branched alcohols [4, 5]. Methanol synthesis catalysts modified with Fischer-Tropsch (FT) elements and modified Mo-catalysts are the second group of HAS catalysts. These catalysts yield a series of linear primary alcohols and gaseous hydrocarbons both with Anderson-Schulz-Flory (ASF) carbon number distribution [6, 7]. Comparatively, molybdenum-sulfide-based catalysts showed a high proportion of higher alcohols at lower pressure and high temperature. MoS2-based catalysts can tolerate sulfur and coke-buildup as a result of higher alcohols synthesis. When MoS2 is promoted with K2CO3, the same performance of the catalysts is achieved at a significantly lower temperature [8]. The alkali-promoted MoS2 catalysts promoted with Co showed high activity to alcohols and can also produce alcohols with a variable ratio of methanol to higher alcohols by changing the operating conditions [9, 10]. The CO hydrogenation was studied over K/Co/Mo/A12O3 and K/Co/Mo/SiO2 catalysts and found that all three elements are necessary for higher activity. Hydrocarbons and alcohols were produced in approximately equal amounts over both the catalysts [11]. Copromotion on alkali-modified MoS2 catalysts leads to the shrinking of MoS2 species, while Co exists
%U http://www.hindawi.com/journals/jcat/2013/942145/