Abstract: Selective and controlled dealumination of an aluminosilicate zeolite is achieved by filling the pore system of the zeolite with a foreign material, for example coke, removing part of the foreign material from the outer portion of the zeolite, for example by heating in a gas stream comprising oxygen, dealuminating the outer portion, and then removing the remainder of the foreign material. Use of such a partially dealuminated zeolite as catalyst in a toluene disproportionation reaction leads to greater selectivity to paraxylene.

Abstract: Selective and controlled dealumination of an aluminosilicate zeolite is achieved by filling the pore system of the zeolite with a foreign material, for example coke, removing part of the foreign material from the outer portion of the zeolite, for example by heating in a gas stream comprising oxygen, dealuminating the outer portion, and then removing the remainder of the foreign material. Use of such a partially dealuminated zeolite as catalyst in a toluene disproportionation reaction leads to greater selectivity to paraxylene.

Abstract: Hydrocarbons e.g. toluene and oxyhydrocarbons e.g. methanol are converted to other hydrocarbons by being contacted under conversion conditions with a catalyst comprising zeolite Nu-5.

Abstract: Novel phosphinites and phosphonites of general formula: ##STR1## where R.sub.2 is an electron-donating substituent, R.sub.1 and R.sub.3 are electron-donating substituents or hydrogen atoms, provided that they are not both hydrogen atoms, or either R.sub.1 or R.sub.3 forms part of a fused alicyclic ring with R.sub.2, R is alkyl or cycloalkyl, and n and m are integers, each being either 1 or 2, provided that (m+n) equals 3, and when n is 2, the substituents on each aromatic ring may be the same or different, and their use as catalysts for the dimerisation of acrylonitrile to give predominantly straight-chain C.sub.6 dimers.

Abstract: Phosphinite and phosphonite compounds selected from the group of isopropyl bis p-isopropoxyphenylphosphinite, isopropyl phenyl(p-methoxyphenyl)phosphinite, isopropyl phenyl (p-isopropoxyphenyl)phosphinite, isopropyl phenyl (p-dimethylaminophenyl)phosphinite, isopropyl phenyl (p-tertiarybutoxyphenyl)phosphinite, di-isopropyl p-isopropoxyphenylphosphonite, di-ethyl p-isopropoxyphenylphosphonite, cyclohexyl bis p-methoxyphenylphosphinite, isopropyl phenyl(p-diethylaminophenyl) phosphinite, isopropyl bis p-methoxyphenylphosphinite, isopropyl bis dimethylaminophenylphosphinite, isopropyl phenyl (p-tertiarybutylphenyl)phosphinite, di-isopropyl p-methoxyphenylphosphonite, di-isopropyl p-dimethylaminophenylphosphonite, di-ethyl p-dimethylaminophenylphosphonite.

Abstract: Process for the dimerization of acrylonitrile to predominantly straight-chain 1,4-dicyanobutenes (DCB). The ACN is contacted with an organic phosphinite or phosphonite having at least one substituted aryl group attached to the phosphorus atom in the presence of an inert proton-donating solvent and, optionally, an inert non-hydroxylic cosolvent preferably a hydrocarbon, the ACN and solvent(s) being substantially dry. Selectivities of 95% or even 98%, with respect to 1,4 - DCN, may be obtained.

Abstract: Process for the dimerization of acrylonitrile to predominantly straight-chain 1,4-dicyanobutenes (DCB). The ACN is contacted with an organic phosphinite or phosphonite in the presence of an inert proton-donating solvent and, optionally, an inert non-hydroxylic co-solvent preferably a hydrocarbon, the ACN and solvent(s) being substantially dry. Selectivities of 95% are obtained with respect to 1,4 - DCB.