Syn-gas conversion

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. 

We have our work divided into process engineering, process chemistry, catalysis, and support technology. As an example, one of the indirect liquefaction projects, tube wall reactor, deals with the design and operation of high thermal efficiency catalytic reactors for syn-gas conversion. Other activities are coal liquefaction properties of coal minerals, the role of catalysts, coal liquid product stability, and environmental impact—to name a few. 

Balachandran et al. (1997) SEM Perovskites (oxides of Sr, Fe, and Co) Phase formation in membrane reactors + + + Oxygen storage for methane-syn gas conversion... 

Although many problems still remain to be overcome to make the process practical (not the least of which is the question of the corrosive nature of aqueous HBr and the minimization of formation of any higher brominated methanes), the selective conversion of methane to methyl alcohol without going through syn-gas has promise. Furthermore, the process could be operated in relatively low-capital-demand-ing plants (in contrast to syn-gas production) and in practically any location, making transportation of natural gas from less accessible locations in the form of convenient liquid methyl alcohol possible. 

Considerable challenges still remain in the development of new carbonylation processes for acetic acid manufacture. For example, all of the current processes use iodide compounds, leading to corrosive HI and the need for expensive materials for plant construction. An iodide-free system could potentially impart considerable benefit. Other long term goals include the selective direct conversion of syn-gas or oxidative carbonylation of methane to acetic acid. Organometallic chemists are certain to play a crucial role if these targets are to be achieved. 

The nucleophilic attack by alkoxides, amines, and water is of great interest to homogeneous catalysis. A dominant reaction in syn-gas systems is the conversion of carbonyls with water to metal hydrides and carbon dioxide ("Shift Reaction"), see Figure 2.27. 

Fischer-Tropsch. Oct-l-ene is produced as one of the many products in the conversion of syn-gas and isolated by careful distillations and extractions of the mixture by Sasol. 

Another, highly selective oligomerisation reaction of ethene should be mentioned here, namely the trimerisation of ethene to give 1-hexene. Worldwide it is produced in a 0.5 Mt/y quantity and used as a comonomer for ethene polymerisation. The largest producer is BP with 40 % market share utilizing the Amoco process, formerly the Albemarle (Ethyl Corporation) process. About 25 % is made by Sasol in South Africa where it is distilled from the broad mixture of hydrocarbons obtained via the Fischer-Tropsch process, the conversion of syn-gas to fuel. The third important process has been developed by Phillips. 

Another important use of methane is its conversion into synthesis gas (or syn-gas), a mixture of hydrogen gas and carbon monoxide as shown in Figure 17.1. Syn-gas can also be derived from coal. When this occurs, it is called water gas. Interestingly, the reaction of methane giving carbon monoxide and hydrogen can be reversed so that methane can be produced from coal through this route. 

This report describes a process to produce vinyl acetate with high selectivity from exclusively methanol, carbon monoxide, and hydrogen. The simplest scheme for this process involves esterifying acetic acid with methanol, converting the methyl acetate with syn gas directly to ethylidene diacetate and acetic acid, and finally, thermal elimination of acetic acid. Produced acetic acid is recycled. Each step proceeds in high conversion and selectivity. 

This report has described the development of a new process in which vinyl acetate is produced exclusively from methanol and syn gas with essentially no by-products. At best conditions, high conversions and selectivities are typical of the chemistry involved. Various process possibilities were described, thus permitting much flexibility for eventual development. 

The conversion of CO + H2 (syn-gas) to hydrocarbons and oxygenates (Fischer-Tropsch chemistry)119 is of considerable industrial importance and recently the activation and fixation of carbon monoxide in homogeneous systems has been an active area for research.120,121 The early transition elements and the early actinide elements, in particular zirconium124 and thorium,125 126 supported by two pentamethylcyclopentadienyl ligands have provided a rich chemistry in the non-catalytic activation of CO. Reactions of alkyl and hydride ligands attached to the Cp2M centers with CO lead to formation of reactive tf2-acyl or -formyl compounds.125,126 These may be viewed in terms of the resonance forms (1) and (2) shown below. 

Biomass gasification (C6H1206) Heat (2) Hydrogen Syn gas (CO+H2) FT oil (4) US, Japan Increase of efficiency and yield of conversion by nuclear enerciv... 

The basic reaction for conversion of syn gas to mixtures of hydrocarbons is called the Fischer-Tropsch reaction, used in Germany during World War II to produce fuel mixtures for diesel and gasoline engines. Since the 1950s South Africa has also used this reaction, and currently there is much interest in using it to convert natural gas (methane) to more easily transported liquids. 

Alper and co-workers improved the asymmetric hydroformylation of vinyl P-lactams. The substitution of a Zwitterionic rhodium catalyst (187) and CS, S )-BDPP (188) in the asymmetric hydroformylation of 185b produced regioselectivities of >99/1 (b/1) and enantioselectivities of >99/1 (1860 18601) with 70% conversion at 1200 psig syn gas (S/C = 20).234 This transformation has been performed at the kilogram scale.235... 

In the Canadian context there need not be a restriction on biomass conversion processes to be self-sufficient and therefore be required to sacrifice carbon to drive the processes, Natural gas and hydro/nuclear electricity are likely to be available on a large scale through to the early decades of the next century. One or all of the following options have been discussed in the context of biomass conversion and in the specific case of methane additions to alter hydrogen to carbon monoxide ratios in syn gas work is presently under way to combine oxygen blown wood gasification with the reforming of natural gas, (5),... 

The role of ceria as oxidant in the conversion of methane to syn-gas under anaerobic conditions has been investigated in recent studies [74-79]. Otsuka et al. have shown that the reaction of methane with ceria in the absence of gaseous oxygen selectively produced a synthesis gas with a H2/CO ratio of 2, while CO2 and HjO... 

With this in mind a methanol economy has been proposed by Olah and coworkers [6] as an alternative, or a previous step, to a future hydrogen ecmiomy . Methanol (CH3OH), is the simplest, safest, and easiest way to store and transport hydrogen as a liquid hydrocarbon. It is prepared almost exclusively from a mixture of CO and H2 (syn-gas) resulting from the incomplete combustion of natural gas or coal. Methanol economy involves not only the use of methanol as a fuel and gasoline additive, but also its conversion to synthetic hydrocarbons and their products and materials, which are essential part of our life [6]. 

Prior to the conversion of the alkene, the Rh/TPPTS catalyst system has to be pre-formed (formation of the Rh-hydrido-carbonyl complex) applying a specific chemical procedure is necessary to form the active Rh(l) species, mostly starting from Rh(lll) precursors. In general this is achieved under hydroformylation conditions. Thus, treatment of the rhodium precursor with syn gas in the absence of alkene for a couple of hours will transform it into a Rh-hydrido-carbonyl complex. 

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