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Abstract

Abbreviations: HA: higher alcohols; FTS: fischer-tropsch synthesis; OCP: other carbon particles; OMC: ordered mesoporous carbon; FTIR: fourier transform infra-red; TEM: transmission emission microscopy IntroductionGasoline blends with up to 10% ethanol (E10) and higher alcohols are commercially available at gasoline pump stations in the USA, Canada, and some parts of Europe. 1 The production of these alcohols (C 2 and C 2+ ) promises immense potential to replace other additives utilized as octane boosters in automotive fuels. Catalytic conversion of synthesis gas (mainly, CO+H 2 ) to higher alcohols (HA) via the Fischer-Tropsch synthesis (FTS) process has received tremendous interest due to the generation of environmentally benign octane boosters and alternative fuels to supplement the diminishing supply of the world's finite fossil fuel reserves. In this regard, beneficial incentives derived from the use of these alcohols as alternative fuels or alternative fuel components in transportation systems directly tackles global climate issues such as the reduction of greenhouse gas emissions, reduction of toxic emissions, and also the improvement of the overall energy efficiency of internal combustion engines.2 Unlike gasoline and diesel fuels, higher alcohols contain oxygen components that allow gasoline-blended fuels to combust more completely; thereby, increasing the combustion efficiency and reducing air pollution, and can also be renewable resource depending on the origin of syngas feedstock (via biomass gasification). To improve selectivity and activity of these alcohol products, the catalyst metals and supports used for this reaction play a vital role. 3In the catalysis of hydrogenation reactions on heterogeneous surfaces, whereby metal precursors dispersed on a porous support act as catalyst, the support plays a crucial role due to the probable hydrogen spillover effect. 4,5 The atomic hydrogen forming as a result of dissociative adsorption on the metal migrates onto the support (hydrogen spillover); making the chemical reaction proceeds not only on the metal surface but also on the support. 5In general terms, the support acts to: a. Stabilize the active species and promoters. b. Promote hydrogen or oxygen donation or exchange.c. Modify the dispersion, reducibility, and electron-donating or accepting effects of metal particles 6 among others.Nevertheless, the nature of surface acidity or basicity of the support can greatly impact the surface chemistry of the final catalysts. For instance, metal oxide supports such as SiO 2 and Al 2 O 3 have the tendency to favour hydrocarbons formation by suppressing the reaction rate of alcohols as a result of accelerated coke deposition. AbstractThe submerged arc discharge in liquid nitrogen technique was used to synthesize carbon nanohorns (CNHs) using 90A and 34V; generating other carbon by-products at the high temperature (>4000K) plasma zone, herein depicted as: "other carbon particles" (OCP) and "other fine carbon particles" (OCP f ). In the present work, a series of ...