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Ethanolamines are conventionally produced on an industrial scale exclusively by the reaction of ethylene oxide (EO) with an aqueous solution of ammonia. The reaction is a typical consecutive reaction with three steps [NH3 → NH2(CH2OH) → NH(CH2OH)2 → N(CH2OH)3]; therefore, it is difficult to produce diethanolamine with high selectivity. We developed a catalytic process for selective diethanolamine production from EO and anhydrous ammonia using a ZSM-5 zeolite catalyst modified with rare earth elements. This highly active catalyst was able to recognize the difference at molecular level between diethanolamine and triethanolamine. We also succeeded in producing a binderless molded zeolite catalyst having a shape suitable for a fixed-bed reactor. This catalyst does not give problematic impurities due to undesirable reactions over binders. The catalyst deterioration was overcome by developing a regeneration process using high temperature and high-density ammonia gas as a rinse medium. [ABSTRACT FROM AUTHOR]

Abstract: We studied the deactivation of silica–alkaline-phosphate catalyst for ethylenimine production by vapor phase intramolecular dehydration of monoethanolamine. There are two types of catalyst deactivation—a short time-range deactivation caused by coking and a long time-range deactivation due to structural changes in the catalyst such as sintering or loss of active component. Catalytic activity decreases along with lowering of the surface area when sintering occurs. Sintering is accelerated by water vapor at high temperature. Loss of phosphorus, which is one of the catalytically active components, also causes deactivation. The lost phosphorus in the catalyst can be resupplied by treatment with volatile phosphorus compounds in the reactor, and catalytic activity and selectivity can be recovered. [Copyright &y& Elsevier]

The selective N-methylation of bifunctionalized amines with supercritical methanol (scCH3OH) promoted by the conventional solid acids (H-mordenite, β-zeolite, amorphous silica-alumina) and acid-base bifunctional catalysts (Cs--P--Si mixed oxide and γ-alumina) was investigated in a continuous-flow, fixed-bed reactor. The use of scCH3OH in the reaction of 2-aminoethanol with methanol (amine/CH3OH = 1/10.8) over the solid catalysts led to a significant improvement in the chemoselectivity of the N-methylation. Among the catalysts examined, the Cs--P--Si mixed oxide provided the most efficient catalyst performance in terms of selectivity and reactivity at 300 °C and 8.2 MPa; the N-methylation selectivity in the products reaching up to 94% at 86% conversion. The present selective methylation was successfully applied to the synthesis of N-methylated amino alcohols and diamines as well as 0-methylated ethylene glycol. Noticeably, ethoxyethylamine was less reactive, suggesting that the hydroxy group of the amino alcohols is a crucial structural factor in determining high reactivity and selectivity, possibly because of the tethering effect of another terminus, a hydroxo group, to the catalyst surface. The magic-angle-spinning NMR spectroscopy and X-ray diffraction analysis of the Cs--P--Si mixed oxide catalyst revealed that the acidic and basic sites originate from P2O5/SiO2 and Cs/SiO2, respectively, and the weak acid-base paired sites are attributed to three kinds of cesium phosphates On SiO2. The weak acid--base sites on the catalyst surface might be responsible for the selective dehydrative methylation. [ABSTRACT FROM AUTHOR]