Catalysts containing liquid fuel

Mechanism of catalyst deactivation during SR of sulphur containing liquid fuel (Lakhapatri and Abraham, 2011). 

The hydroformylation of alkenes was accidentally discovered by Roelen while he was studying the Fischer-Tropsch reaction (syn-gas conversion to liquid fuels) with a heterogeneous cobalt catalyst in the late thirties. In a mechanistic experiment Roelen studied whether alkenes were intermediates in the "Aufbau" process of syn-gas (from coal, Germany 1938) to fuel. He found that alkenes were converted to aldehydes or alcohols containing one more carbon atom. It took more than a decade before the reaction was taken further, but now it was the conversion of petrochemical hydrocarbons into oxygenates that was desired. It was discovered that the reaction was not catalysed by the supported cobalt but in fact by HCo(CO)4 which was formed in the liquid state. 

Deactivation of catalysts in the reforming of liquid fuels is caused principally by two processes the formation of carbon-containing deposits and sulfur poisoning. This section examines the thermodynamics and the literature dealing with these processes. 

The new Brownsville, Tex., plant for the manufacture of synthetic liquid fuels from natural gas makes use of this reaction to increase the octane number of its product by as much as 20 units. Synthetic naphtha produced over iron catalyst is highly olefinic and contains substantial amounts of straight-chain isomers with terminal double bonds (8). The shifting of these double bonds toward the center of the molecule may be accomplished by vapor-phase treatment employing synthetic cracking catalyst in the fluid state, under mild catalytic cracking conditions. Oxygenated compounds also present are converted under the isomerization conditions to hydrocarbons and water. 

Many research studies have been carried out to examine the possibilities for conversion of biomass feedstocks to liquid products by direct thermochemical treatment. These studies include the treatment of aqueous and nonaqueous slurries of wood particles with different reactants and catalysts at elevated temperatures and pressures, and the pyrolysis of wood under conditions that maximize liquid yields (Chapter 8). The prime objective was to develop processes for production of liquid fuels and not chemicals. The resulting products are generally acidic and contain high concentrations of carboxylic acids, phenolic compounds, and heterocyclic oxygen and alicyclic oxygenated compounds. With only a few exceptions, the products contain low concentrations of BTX. 

In previous studies the authors have reported that metals oxides such as GaaOa, AI2O3, Zr02 and Cr203 contained in Cu/ZnO-based catalysts have an important role to improve simultaneously the activity and the selectivity[1, 2]. Unlike Cu/ZnO-based catalysts, Raney copper catalysts have not been widely reported in the literature as practical catalysts for methanol synthesis. However, 20 years ago Wainwright and co-workers have been the first to report the potentiel use of Raney Cu and Raney Cu-Zn as catalysts to produce methanol from syngas to use as synthetic liquid fuel [3]. Recent works of Wainwright et al. on methanol synthesis... 

An application of microfluidic reactors is the development of a membraneless fuel cell. Two streams, one containing a fuel such as methanol, the other an oxygen-saturated acid or alkaline stream, are merged without mixing. The laminar flow pattern in the narrow channel helps to maintain separate streams without the use of membrane separators. Opposite walls function as the electrodes and are doped with catalyst. Ion exchange, protons for the add system, takes place through the liquid-liquid interface. This is an example of a solid-liquid-liquid-solid multiphase reactor. ... 

Mixtures of carbon monoxide, carbon dioxide, hydrogen and water as formed by the reaction of steam on hot carbon are frequently found to contain methane. Methane formation may result from a variety of different reactions and its quantity depends upon the condition of the experiment i.e., temperature, pressure, the relative proportions of the gases, and the catalysts present. The phenomena involved in the formation of methane have been the subject of investigations which have extended over a long period of time and which have been undertaken largely with two objects in mind first, the enrichment of water-gas for illuminating purposes, and second, the utilization of coal as a source of liquid fuels.3 It seems desirable at this point to review briefly the earl - history of these developments.4... 

Fig. 5.6-4 Schematic illustration of a supported ionic liquid fuel cell containing the Wacker oxidation system (SMSEC supported molten salt electro-catalyst) for co-generatlon of acetaldehyde and electricity from ethanol [55],...

Other process concepts similar to those outlined previously have also appeared in the literature from time to time and an example of such a process is the disposable catalyst process (Figure 19.21) in which the coal (dried and slurried with a recycle oil) is mixed with an iron-containing (red mud) catalyst after which hydrogen (2000-4000 psi) is added and the whole is introduced into the reactor. The reactions occur in the liquid phase and the liquid product is separated by distillation to produce a liquid fuel oil and a heavier slurrying oil as well as residuum-type oil. This latter product may be processed further to yield further quantities of lighter products. 

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