Monsanto catalyst

In SILP carbonylation we have introduced a new methanol carbonylation SILP Monsanto catalyst, which is different from present catalytic alcohol carbonylation technologies, by using an ionic liquid as reaction medium and by offering an efficient use of the dispersed ionic liquid-based rhodium-iodide complex catalyst phase. In perspective the introduced fixed-bed SILP carbonylation process design requires a smaller reactor size than existing technology in order to obtain the same productivity, which makes the SILP carbonylation concept potentially interesting for technical applications. 

Using a Monsanto catalyst system (Rh/Mel/CO) the carbonylation of methyl acetate has a long induction period in the absence of water and a low reaction rate in comparison with the synthesis of acetic acid under typical reaction conditions. 

The Monsanto catalyst system has been the subject of numerous studies (for leading references see [6-12,16,18]). The rate of the overall carbonylation process is zero order in each of the reactants (MeOH and CO) but first order in the rhodium catalyst and in the methyl iodide cocatalyst,... 

Although the Monsanto catalyst is a great improvement over the original BASF catalyst, it suffers from the following drawbacks Rh is very expensive and any losses even in trace amounts have a direct impact on process economics, and Rh reserves are limited and available only in certain regions. The latter is a matter of great concern in view of the continuous growth in acetic acid capacity. 

This group demonstrated that both dinuclear complexes 38 and 40 exhibit a remarkably better activity than the mononuclear complexes 39 and 41 at equivalent metal-catalyst concentrations (Table 22.19). The reaction was evaluated/tested against the Monsanto catalyst [Rhl2(CO)2l used in industrial processes, which is formed in situ from [ RhCl(CO)2 2]. In the carbonylation of methanol, 38 outperformed the Monsanto catalyst, whereas 40 demonstrated a similar turnover number. The exceptionally good reactivity could be explained by the formation of thermally stable metal chelate complexes, due to the ort/ o-carborane(12) backbone. NMR spectra of the residue at the end of the reaction showed a high content of phosphine bound to rhodium with a retained bimetallic structure, indicated by the chemical shifts and coupling constants. 

The use of symmetrical diphosphines has been covered by the patent literature,and when using xantphos derivatives 29-38 as ligands for methanol carbonylation, they are stable systems that show a slightly higher activity than the one obtained with the Monsanto catalyst. Nevertheless, in this case, a terdentate P-O-P coordination of the ligand is claimed. 

CO, and methanol react in the first step in the presence of cobalt carbonyl catalyst and pyridine [110-86-1] to produce methyl pentenoates. A similar second step, but at lower pressure and higher temperature with rhodium catalyst, produces dimethyl adipate [627-93-0]. This is then hydrolyzed to give adipic acid and methanol (135), which is recovered for recycle. Many variations to this basic process exist. Examples are ARCO s palladium/copper-catalyzed oxycarbonylation process (136—138), and Monsanto s palladium and quinone [106-51-4] process, which uses oxygen to reoxidize the by-product... 

This reaction is rapidly replacing the former ethylene-based acetaldehyde oxidation route to acetic acid. The Monsanto process employs rhodium and methyl iodide, but soluble cobalt and iridium catalysts also have been found to be effective in the presence of iodide promoters. 

Ca.ta.lysis, The readily accessible +1 and +3 oxidation states of rhodium make it a useful catalyst. There are several reviews of the catalytic properties of rhodium available (130—132). Rhodium-catalyzed methanol carbonylation (Monsanto process) accounted for 81% of worldwide acetic acid by 1988 (133). The Monsanto acetic acid process is carried out at 175°0 and 1.5 MPa (200 psi). Rhodium is introduced as RhCl3 but is likely reduced in a water... 

Liquid-Ph se Processes. Prior to 1980, commercial hquid-phase processes were based primarily on an AIQ. catalyst. AIQ. systems have been developed since the 1930s by a number of companies, including Dow, BASF, Shell Chemical, Monsanto, SociStH Chimique des Charboimages, and Union Carbide—Badger. These processes generally involve ethyl chloride or occasionally hydrogen chloride as a catalyst promoter. Recycled alkylated ben2enes are combined with the AIQ. and ethyl chloride to form a separate catalyst—complex phase that is heavier than the hydrocarbon phase and can be separated and recycled. 

In 1974, Monsanto brought on-stream an improved Hquid-phase AIQ. alkylation process that significantly reduced the AIQ. catalyst used by operating the reactor at a higher temperature (42—44). In this process, the separate heavy catalyst—complex phase previously mentioned was eliminated. Eliminating the catalyst—complex phase increases selectivities and overall yields in addition to lessening the problem of waste catalyst disposal. The ethylben2ene yields exceed 98%. 

Currently, almost all cumene is produced commercially by two processes ( /) a fixed-bed, kieselguhr-supported phosphoric acid catalyst system developed by UOP and (2) a homogeneous AlCl and hydrogen chloride catalyst system developed by Monsanto. 

AlCl and Hydrogen Chloride Catalyst. Historically, AIQ processes have been used more extensively for the production of ethylbenzene than for the production of cumene. In 1976, Monsanto developed an improved cumene process that uses an AIQ. catalyst, and by the mid-1980s, the technology had been successfully commercialized. The overall yields of cumene for this process can be as high as 99 wt % based on benzene and 98 wt % based on propylene (60). 

Aluminum Chloride-Based All lation. The eadier alkylation processes were variations of the Eriedel-Craft reaction on an aluminum chloride catalyst complex in a Hquid-phase reactor (27), including those developed by Dow Chemical, BASE, Monsanto, and Union Carbide in cooperation with Badger. The Union Carbide-Badger process was the one most widely used during the 1960s and 1970s, with 20 plants built worldwide. 

Acetic acid from methanol by the Monsanto process, CH3OH -1-CO CH3COOH, rhodium iodide catalyst, 3 atm (44 psi), 150°C (302°F), 99 percent selectivity of methanol. 

In 1968 the Monsanto Company announced the availability of novel soluble low molecular weight polyphenylene resins. These may be used to impregnate asbestos or carbon fibre and then cross-linked to produce heat-resistant laminates. The basic patent (BP 1037111) indicates that these resins are prepared by heating aromatic sulphonyl halides (e.g. benzene-1,3-disulphonyl dichloride) with aromatic compounds having replaceable nuclear hydrogen (e.g. bisphenoxy-benzenes, sexiphenyl and diphenyl ether). Copper halides are effective catalysts. The molecular weight is limited initially by a deficiency in one component. This is added later with further catalyst to cure the polymer. 

Alternative approaches using Friedel-Crafts catalysts were developed independently by Phillips and Harris " at about the same time as the Monsanto developments. 

Other catalyst systems such as iron V2O5-P2O5 over silica alumina are used for the oxidation. In the Monsanto process (Figure 6-4), n-butane and air are fed to a multitube fixed-bed reactor, which is cooled with molten salt. The catalyst used is a proprietary modified vanadium oxide. The exit gas stream is cooled, and crude maleic anhydride is absorbed then recovered from the solvent in the stripper. Maleic anhydride is further purified using a proprietary solvent purification system. ... 

In the Monsanto/Lummus Crest process (Figure 10-3), fresh ethylbenzene with recycled unconverted ethylbenzene are mixed with superheated steam. The steam acts as a heating medium and as a diluent. The endothermic reaction is carried out in multiple radial bed reactors filled with proprietary catalysts. Radial beds minimize pressure drops across the reactor. A simulation and optimization of styrene plant based on the Lummus Monsanto process has been done by Sundaram et al. Yields could be predicted, and with the help of an optimizer, the best operating conditions can be found. Figure 10-4 shows the effect of steam-to-EB ratio, temperature, and pressure on the equilibrium conversion of ethylbenzene. Alternative routes for producing styrene have been sought. One approach is to dimerize butadiene to 4-vinyl-1-cyclohexene, followed by catalytic dehydrogenation to styrene ... 

William Knowles at the Monsanto Company discovered some years ago that u-amino acids can be prepared enantioselectively by hydrogenation of a Z enam-ido acid with a chiral hydrogenation catalyst. (S)-Phenylalanine, for instance, is prepared in 98.7% purity contaminated by only 1.3% of the (H) enantiomer when a chiral rhodium catalyst is used. For this discovery, Knowles shared the 2001 Nobel Prize in chemistry. 

More recently there have been developed water- resistant phosphorus-based intumescence catalyst. This commercially available product, as an example Phos-Chek P/30 tradename from Monsanto, can be incorporated (with other water insoluble reagents) into water-resistant intumescent coatings of either the alkyd or latex-emulsion type. These intumescent coatings, formulated ac-... 

Such a complex, cw-Rh(CO)2I2, is the active species in the Monsanto process for low-pressure carbonylation of methanol to ethanoic acid. The reaction is first order in iodomethane and in the rhodium catalyst the rate-determining step is oxidative addition between these followed by... 

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