Mobil gasoline synthesis

Poutsma ML. Assessment of Advanced Process Concepts for Liquefaction of Low H2/CO Ratio Synthesis Gas Based on the Kolbel Slurry Reactor and the Mobil-Gasoline Process. ORNL Report ORNL-5635 1980. National Technical Information Service, US Dept of Commerce, Springfield. 

By selection of appropriate operating conditions, the proportion of coproduced methanol and dimethyl ether can be varied over a wide range. The process is attractive as a method to enhance production of Hquid fuel from CO-rich synthesis gas. Dimethyl ether potentially can be used as a starting material for oxygenated hydrocarbons such as methyl acetate and higher ethers suitable for use in reformulated gasoline. Also, dimethyl ether is an intermediate in the Mobil MTG process for production of gasoline from methanol. 

Hydrocarbons from Synthesis Gas and Methanol. Two very important catalytic processes in which hydrocarbons are formed from synthesis gas are the Sasol Eischer-Tropsch process, in which carbon monoxide and hydrogen obtained from coal gasification are converted to gasoline and other products over an iron catalyst, and the Mobil MTG process, which converts methanol to gasoline range hydrocarbons using ZSM-5-type 2eohte catalysts. 

One shortcoming of the Fischer-Tropsch synthesis is its lack of selectivity in giving complex product mixtures. In an attempt to improve the selectivity of syngas-based hydrocarbon synthesis, Mobil researchers developed a process consisting of converting methyl alcohol (itself, however, produced from syngas) to gasoline (or other hydrocarbons) over a shape-selective intermediate-pore-size zeolite catalyst (H-ZSM-5) 22 78... 

Whatever the source of synthesis gas, it is the starting point for many industrial chemicals. Some examples to be discussed are the hydroformylation process for converting alkenes to aldehydes and alcohols, the Monsanto process for the production of acetic acid from methanol, the synthesis of methanol from methane, and the preparation of gasoline by the Mobil and Fischer-Tropsch methods. 

Both the Fischer-Tropsch reaction and the Mobil process enable one to convert synthesis gas into hydrocarbons. Since synthesis gas may be obtained from coal, we have in effect a means of converting coal u> gasoline. Geimany moved its Panzer Korps in World War II with synthetic fuels made from (he Fischer-Tropsch reaction, and improved technological developments have enhanced the attractiveness of the process. South African Synthetic Oil Limiied fSASOLJ currently operates several modern Fischer-Tropsch plants. Many organometallic chemists refer to both the Fischer-Tropsch and Mobil processes as political processes 1 2 because they are heavily subsidized by countries that find it important to be independent of foreign oil. 

This is an important industrial reaction, alone or in combination with others. The CH3OH production is often coupled to oxidation to formaldehyde, methanol to gasoline (Mobil) process, methanol to olefins process, carbonylation, etc. Due to this, a large volume of information already exists on catalyst preparation, kinetics, reactors and all other aspects of the related chemical technology [53]. However, let us concentrate our attention here on just one selected problem the role of the promoter and the nature of the active site on the metal on oxides catalysts. Let us mention in passing that pure metals (promoter free) most likely do not catalyze the synthesis. 

Another key step was the demonstration by P.B. Weisz and coworkers (3-5) of the shape selectivity of zeolite catalysts related to molecular sieving (1960). This initiated further research in the synthesis of new zeolites as well as industrial applications based on this property. The first commercial shape-selective process, Selectoforming, was developed by Mobil (1968) and allowed the selective cracking of the low octane (n-alkane) components of light gasoline over a natural zeolite (erionite) (6). 

One of the most significant stages in the development of zeolite catalysts was the synthesis by Mobil scientists (U.S. Patent 3,702, 866) of the zeolite now universally known as ZSM-5 (i.e. Zeolite Socony Mobil-5). This was the first - and most important - member of a new class of shape selective catalysts, which have made viable the production of synthetic gasoline . In this process, high-octane gasoline is produced by the catalytic conversion of methanol to a mixture of aromatic and aliphatic hydrocarbons (Derouane, 1980). Because of its unique combination of chemical nature and pore structure, ZSM-5 is a highly effective dehydration, isomerization and polymerization catalyst. 

The production of gasoline from methanol is a parallel process to the Fischer-Tropsch synthesis of hydrocarbons from syngas (Section 4.7.2). A shape-selective zeolite (ZSM-5) was the catalyst of choice in the process put on stream in 1987 by Mobil in New Zealand however the plant was later closed. The zeolite was used at ca. 400°C in a fluid catalyst reactor, which allows prompt removal of the heat of reaction. 

Syngas conversion to methanol has been shown to take place on supported palladium catalyst [1]. Methanol can in turn be converted to gasoline over ZSM-5 via the MTG process developed by Mobil [2]. In recent work we have reported syngas (CO/H2) conversion to hydrocarbon products on bifunctional catalysts consisting of a methanol synthesis function, Pd, supported on ZSM-5 zeolites [3]. Work on syngas conversion to hydrocarbon products on Pd/SAPO molecular sieves has been published elsewhere [Thomson et. al., J. CataL. in press].Therefore, this paper will concentrate on propylene conversion. 

Existing routes for methane conversion (Fischer-Tropsch and Mobil methanol-to-gasoline processes) require, as the first step, the production of synthesis gas (CO and H2) from methane by the costly and inefficient process of steam reforming. These routes are nonetheless accepted technologies since to date it has not been possible to achieve large-scale conversion of methane directly to higher hydrocarbons. 

Reforming of methane to synthesis gas for subsequent conversion to methanol or production of gasoline and diesel fuels from methanol via Mobil technology is commercially available. 

Natural gas, by direct partial oxidation, can provide olefins suitable for oligomerisation using the Mobil Olefin to Gasoline and Diesel process. Alternatively, synthesis gas routes to olefins can be via methanol or Fischer-Tropsch synthesis. In the Fischer-Tropsch option, the hydrogen-rich nature of the synthesis gas requires that the catalyst should have poor shift activity and produce a narrow range of lower olefins. 

A new process that converts propylene and water to diisopropyl ether (DIPE) was developed by Mobil Research Development Corp. DIPE is a high-octane gasoline blending agent which, unlike other ethers, utilizes propylene in its synthesis. The DIPE reaction takes place in a fixed-bed catalytic reactor via a series of reaction steps. Isopropyl alcohol (IPA) is an intermediate which is recycled within the process. A propane/propylene splitter is included in the feed purification section to increase the concentration of propylene in the feed and maximize the DIPE production. DIPE utilizes propylene from the refinery and does not depend on an outside supply of alcohol. DIPE has similar octane blending values of RON and MON as other ethers like MTBE and TAME. DIPE also has a lower Reid vapor pressure than that of MTBE. DIPE is virtually nontoxic and has not caused adverse systemic effects or tissue toxicity [66]. 

---