Magnesia catalysts

In some parts of the world, as in Russia, fermented alcohol can serve as a cheap source for hutadiene. The reaction occurs in the vapor phase under normal or reduced pressures over a zinc oxide/alumina or magnesia catalyst promoted with chromium or cohalt. Acetaldehyde has been suggested as an intermediate two moles of acetaldehyde condense and form crotonaldehyde, which reacts with ethyl alcohol to give butadiene and acetaldehyde. 

SEGAS [Southeastern Gas] Also written Seagas. An oil gasification process in which oil is sprayed into a stream of superheated steam and cracked over a calcia/magnesia catalyst. Developed by the Southeastern Gas Board, United Kingdom. 

It may be mentioned here that the first example in which the author tried to apply the principle contained in this paper was on the hydrolysis of methanol (19) (cf. p. 315) with a copper-magnesia catalyst. This reaction is, of course, heterogeneous. 

Commercial production of synthetic silica-alumina catalysts for use in fluid cracking was initiated in 1942. The synthetic catalysts were first manufactured in ground form, but means were later developed for production in MS (micro-spheroidal) form. First shipments of the MS catalyst were made in 1946. The synthetic catalysts contain 10 to 25% alumina. Synthetic silica-magnesia catalyst has also been used commercially in fluid-catalyst units (19,100). Magnesia content is 25 to 35% as MgO (276). 

Silica- magnesia Catalyst Activated clay Silica- alumina... 

Figure 3 shows FTIR spectra of CO adsorption on nickel magnesia catalysts. On Nim Mg(,2>oO and Ni/MgO catalysts, linear (2100-2000 cm ), bridge (2000-1850 cm ) and physisorbed Ni(CO)4 (2057 cm ) were mainly observed. In contrast, on NidojMgo O nickel monomer and dimer carbonyl species which are interacted with MgO were mainly observed as previously reported[10]. These species were increased with the CO pressure, therefore they are found to be formed via CO induced structural change. On NioojMgj O solid solution, Ni metal particles seem to be highly dispersive. 

Sidjabat, O. and Trimm, D.L. Nickel-magnesia catalysts for the steam reforming of light hydrocarbons. Topics in Catalysis, 2000, 11-12 (1), 279. 

Here we intended to study the DC conductivity, oxygen isotope exchange, andTPD techniques which give the active site information at the high temperature [10]. Two kinds of magnesia catalysts, i.e., MgO and Li/MgO were studi. The defect notations follow after Kroger [11]. 

Silica from three sources was added to an iron- copper-magnesia catalyst and the activity for the conversion of syngas to middle distillate for the catalysts with and without silica was studied in a 150 ml Fixed Bed Single Tube Reactor. The study revealed that silica additive changes the activity and this change depends on the source of silica and the associated ingradients. 

The silica-magnesia catalysts, DA-5 and Nalco, in the virgin state, along with Davison silica gel have practically their entire area and pore volume contributed by the very smallest of pores that are encountered in catalyst structures that is, pores in the 10 to 15 A. radius range. It is apparent in Fig. 2 that for these materials there is no appreciable adsorption at the high relative pressures. This indicates the absence of large pores. One and one-half monolayers according to the BET theory effectively fill the pore volume of the DA-5 and the Davison silica gel, and only two monolayers are required for Nalco. Very little hysteresis is observed for any of these three materials. 

In Fig. 5 the striking similarity of the isotherms for a virgin DA-5 and a steam-treated DA-5 is apparent. The pore volume and area of the steam-sintered sample are far below those of the virgin, but the isotherm contours are almost identical. A small increase in pore radius is observed. Thus the presence of steam during sintering does not alter significantly the pore structure of the silica-magnesia catalysts studied. It should also be noted here that the isotherms for the DA-5 catalyst... 

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