Loop reactor staged with structured fibrous catalytic layers for liquid-phase hydrogenations

A novel concept of a recycle loop reactor is developed with structured filamentous catalysts integrated as trays in a staged bubble column. The reactor can be operated in batch or continuous mode. Woven fabrics of activated carbon fibers (ACF) were used as support for the Pd catalyst. The loop reactor was tested in the 2-butyne-1,4-diol hydrogenation showing selectivity up to 97% towards 2-butene-1,4-diol at conversions up to 80%. The reactor behavior was described quant. assuming an ideally mixed reactor and Langmuir-Hinshelwood kinetics with weak hydrogen adsorption. Catalyst reuse was demonstrated in multiple runs over a period of 6 mo with more than 375 h on stream. [on SciFinder (R)

Palladium supported on filamentous active carbon as effective catalyst for liquid-phase hydrogenation of 2-butyne-1,4-diol to 2-butene-1,4-diol

Structured palladium catalysts suitable for three-phase reactions have been developed based on woven fabrics of active carbon fibers (ACF) as the catalytic supports. The Pd/ACF were tested in liq.-phase hydrogenation of 2-butyne-1,4-diol showing a selectivity towards 2-butene-1,4-diol up to 97% at conversions up to 80%. Multiple reuse of the catalyst with stable activity/selectivity in a batch reactor was also demonstrated. The reaction kinetics was studied and the main kinetic parameters were obtained. Assuming a Langmuir-Hinshelwood kinetics and a weak hydrogen adsorption a suitable kinetic model was developed consistent with the exptl. data. [on SciFinder (R)

Process for the preparation of 2-butene-1.4-diol

NOVELTY - A 2-butene-1,4-diol is prepared by hydrogenating 2-butyne-1,4-diol in the presence of a structured catalyst and in the absence of a solvent. USE - For preparing 2-butene-2,4-diol that is an important industrial intermediate in the preparation of vitamin B6, pharmaceuticals, and insecticides. ADVANTAGE - The 2-butene-1,4-diol can be prepared in high yield and selectivity by catalytic hydrogenation of 2-butyne-1,4-diol over a structured catalyst in the absence of a solvent. Since hydrogen is sparingly soluble in solvents, e.g. water, the absence of such solvents increases the economy of the hydrogenation process in that it results in higher turnover per time unit. The process avoids separation and recycling of a solvent for environmental protection