摘要:
The aldolization is characterized by the use of a solid basic catalyst which has the following general formula �(Mg.sup.2+).sub.1-x (Al.sup.3+).sub.x (OH.sup.-).sub.2 !.sup.+x �(OH.sup.-).sub.x (H.sub.2 O).sub.n !.sup.-x (II) wherein 0.20.ltoreq.x.ltoreq.0.33 and n has a value of less than 1. This catalyst has a defined crystal structure similar to that of hydrotalcite or, alternatively, of meixnerite. Also disclosed are processes for the preparation of the catalyst.
摘要翻译:醛固化的特征在于使用具有以下通式[(Mg2 +)1-x(Al3 +)x(OH-)2] + x [(OH-)x(H2O)n] -x的固体碱性催化剂 (II),其中0.20≤x≤0.33且n的值小于1.该催化剂具有与水滑石相似的限定的晶体结构,或者替代地,镁石。 还公开了制备催化剂的方法。
摘要:
The invention relates to the use of compounds of formula:[M(II).sub.1-x M*(III).sub.x (OH).sub.2+x ].mH.sub.2 O (I)in which M(II) represents a divalent cation chosen from the group consisting of nickel, zinc, cobalt, magnesium or the mixture of two or more of the abovementioned metals; M(III) represents a trivalent cation, such as aluminum, gallium, iron or chromium, with the exception of the compound of formula (I) in which M(II) is magnesium and M(III) is aluminum, x is between 0.20 and 0.33 and m.ltoreq.1; in the preparation of .beta.-hydroxycarbonyl and/or .alpha.,.beta.-unsaturated carbonyl compounds.
摘要:
There are provided clays of laminated structure bridged by metallic oxides selected from oxides of aluminum and zirconium and containing from 10 to 50% and preferably from 20 to 40% of an oxide of the metal of the group of the lanthanides, preferably of cerium. The presence of cerium improves the thermal resistance during a dry calcination or even under humid air. The clays can be used as catalysts during the conversion of hydrocarbons.
摘要:
A process is provided for the preparation of a catalyst which is particualrly active and selective in the oxidative conversion of methane into higher hydrocarbons and especially into C.sub.2.sup.+ hydrocarbons.In the process, an aqueous phase containing in solution cations of at least one metal of the lanthanide group and cations of at least one alkaline-earth metal, is brought into contact with a sufficient quantity of a source of carbonate ions or hydroxide ions to form a coprecipitate of carbonates and/or of hydroxycarbonates of the metals, the pH of the resulting reaction medium is brought to a value higher than 8, a coprecipitate is separated from the reaction medium, subjected to a washing operation, then to a drying operation and the washed and dried coprecipitate is subjected to calcination.