Methanol, reaction catalyst

Feedstock Reactions Catalyst References Acetone Condensation-hydrogenation (bifunctional catalysis) Pd on sulfonated PS-DVB [6] Methanol, Raffinate II Condensation, hydrogenation Pd on sulfonated PS-DVB [61] Dioxygen dissolved in water Hydrogenation Pd on sulfonated PS-DVB [8]... 

Copper based catalysts have long been considered as the only effective methanol synthesis catalysts. However, Poutsma et al. (7) showed that palladium catalysts were active in methanol synthesis from CO-H. This latter metal had been previously considered as either almost inactive or active only for methane formation (8). Furthermore it is now known that both activity and selectivity can change drastically with the support. Vannice (9) observed that the methanation activity of a Pd/Al O was enhanced eighty and forty times compared to palladium black or Pd/SiO (or Pd/TiO ) respectively. The support effect on the selectivity was pointed out by many authors even at atmospheric pressure when the reaction temperature... 

Figure 7 depicts a simplified block flow diagram (BFD) for a typical biodiesel production process using base catalysis. In the first step, methanol and catalyst (NaOH) are mixed with the aim to create the active methoxide ions (Figure 4, step 1(b)). Then, the oil and the methanol-catalyst solution are transferred to the main reactor where the transesterification reaction occurs. Once the reaction has finished, two distinct phases are formed with the less dense (top) phase containing the ester products and unreacted oil as well as some residual methanol, glycerol, and catalyst. The denser (bottom) layer is mainly composed of glycerin and methanol, but ester residues as well as most of the catalyst, water, and soap can also be found in this layer. 

Several mixed-metal clusters containing platinum and cobalt are known and some of them have been employed as methanol homologation catalysts.1 Among them, the title compound2 was first prepared unambiguously from the reaction of dichloro[l,2-ethanediylbis(diphenylphosphine)]platinum with sodium tetracarbonylcobaltate, Na[CO(CO)4]. The compound also may be prepared by the reaction of [l,2-ethanediylbis(diphenyl-phosphine)]bis(phenylethynyl)pIatinum with Co COJg.1... 

Although numerous investigations have been performed on methanol synthesis catalysts, the structure of the active catalysts, the nature of the active sites, and the reaction mechanism are still subjects of considerable controversy. 

Ammonia, Hydrogen, and Methanol Production The ammonia synthesis catalyst is metallic iron promoted with AljO,. K 0. MgO. and CaO. The hydrogen-producing (methane reforming) catalyst is supported nickel. The methanol synthesis catalyst is ZnO promoted with Cr Oj or Cu(l>—ZnO promoted with CrjOl or AUOi. The respective reactions are cited as follows. 

Deng and co-workers have also applied the cinchona derivatives to the kinetic resolution of protected a-amino acid N-carboxyanhydrides 51 [48]. A variety of alkyl and aryl-substituted amino acids may be prepared with high se-lectivities (krei=23-170, see Scheme 10). Hydrolysis of the starting material, in the presence of the product and catalyst, followed by extractive workup allows for recovery of ester, carboxylic acid, and catalyst. The catalyst may be recycled with little effect on selectivity (run 1, krei=114 run 2, krei=104). The reaction exhibits first-order dependence on methanol and catalyst and a kinetic isotope effect (A MeOH/ MeOD=l-3). The authors postulate that this is most consistent with a mechanism wherein rate-determining attack of alcohol is facilitated by (DHQD)2AQN acting as a general base. 5-Alkyl 1,3-dioxolanes 52 may also... 

As in the case of normal supported catalysts, we tried with this inverse supported catalyst system to switch over from the thin-layer catalyst structure to the more conventional powder mixture with a grain size smaller than the boundary layer thickness. The reactant in these studies (27) was methanol and the reaction its decomposition or oxidation the catalyst was zinc oxide and the support silver. The particle size of the catalyst was 3 x 10-3 cm hence, not the entire particle in contact with silver can be considered as part of the boundary layer. However, a part of the catalyst particle surface will be close to the zone of contact with the metal. Table VI gives the activation energies and the start temperatures for both methanol reactions, irrespective of the exact composition of the products. 

Initially, the reactor was charged with 400 g of rapeseed oil and heated to the set temperature with agitation. Catalyst was dissolved in the required amount of methanol and heated to the set temperature. After reaching the set temperature of reactant and catalyst, methanolic catalyst was added to the base of the reactor to prevent evaporation of methanol. The reaction was timed immediately after the addition of catalyst and methanol. Reaction experiment parameters were designed to determine the conversion yield of rapeseed oil (Table 2). 

As in the case of the fluorination of alkenes in methanol, reaction with 1,3-dienes depends strongly on the catalyst used, and five products were formed by reaction of 2,3-dimethyl-1,3-butadiene when hydrogen fluoride or boron trifluoride were used as catalysts83 (Scheme 27). 

MSR is also carried out on methanol synthesis catalysts at similar temperatures (see Section 5.3.7), but unlike methanol synthesis, it is not subject to thermodynamic constraints. Thermodynamic considerations play a lesser role in MSR, as the inverse of reactions (1) and (2) can be considered irreversible at atmospheric pressure. 

Many studies of simultaneous adsorption of hydrogen or water and CO or C02 have been carried out on the high-pressure methanol synthesis catalysts based on zinc oxide and one or several other oxides, but only three investigations (104, 113, 114) dealt with catalysts containing copper, and two of these were made in reference to the mechanism of the low-temperature shift reaction. 

Initially, the different complexes were tested in the methanolysis of soybean oil at 80°C using the molar ratio 400 100 1 (methanol oil catalyst). It is worth mentioning that these conditions are probably not optimal to obtain the highest reaction yields for all systems. However, this procedure was useful to compare the catalytic activities of the different catalysts. After 3 h, conversions up to 90%, 28%, 15%, and 2%, respectively for the complexes 1, 4,2, and 3 were observed. Using similar conditions (temperature and molar ratio) other Sn+4 complexes were also studied, showing lower activities when compared to complex 1 (Meneghetti et al., 2007). 

JM proprietary methanol synthesis catalyst is packed in the shell side of the reactor. Reaction heat is recovered and used to efficiently generate steam in the tube side. Reactor effluent gas is cooled to condense the crude methanol. The crude methanol is separated in a separator (10). The unreacted gas is circulated for further conversion. A purge is taken from the recycling gas used as fuels in the reformer (3). 

The synthesis loop consists of a recycle compressor, feed/effluent exchanger, methanol reactor, final cooler and crude methanol separator. Uhde s methanol reactor is an isothermal tubular reactor with a copper catalyst contained in vertical tubes and boiling water on the shell side. The heat of methanol reaction is removed by partial evaporation of the boiler feedwater, thus generating 1-1.4 metric tons of MP steam per metric ton of methanol. Advantages of this reactor type are low byproduct formation due to almost isothermal reaction conditions, high level heat of reaction recovery, and easy temperature control by... 

---