Highly Selective Silica‐supported Copper Catalysts Derived from Copper Phyllosilicates in the Hydrogenation of Adipic Acid to 1,6‐hexanediol

Abstract

Hydrogenation of adipic acid (AA) is a potential way to prepare 1,6‐hexanediol (HDOL). Herein, silica‐supported copper catalysts derived from copper phyllosilicates were synthesized, characterized, and tested in the hydrogenation of AA to HDOL. In a full conversion of AA, a high yield of HDOL (approximately 90 %) was obtained through the use of each Cu‐based catalyst. The turnover frequency calculated according to the consumption rate of AA was discovered to be dependent on the Cu+/(Cu0+Cu+) ratio and the reduction condition. Moreover, recycling tests showed that a catalyst derived from a copper phyllosilicate had better stability compared with Cu/SiO2 made through impregnation due to a stronger interaction between Cu and silica. The kinetic analyses based on the global rate expression and Langmuir−Hinshelwood−Hougen−Watson (LHHW) formalism of AA conversion were conducted. The possible competitive adsorption between AA and its derivatives, including hydroxycaproic acid and ϵ‐caprolactone, was thereby revealed.

Copper Phyllosilicates-Derived Catalysts in the Production of Alcohols from Hydrogenation of Carboxylates, Carboxylic Acids, Carbonates, Formyls, and CO2: A Review

“…Wen et al [201] and Popa et al [79] indicated the dissolution of silica from the support evidenced by the formation of tetramethoxysilane (TMOS) in the resultant solution of DMO hydrogenation. ICP analysis indicated that more than 55% of Cu was leached out after three consecutive cycling runs of AA hydrogenation [111]. Deactivation of CuPScats was expected in hydrogenation of AA [119] and LA [175] accompanying the decline of Cu loading after each cycling run (Table 2).…”

“…To transform CuPS precursors into CuPS-cats, a designed temperature-programmed reduction in H2 atmosphere (H2-TPR) is needed. The H2-TPR profiles of CuPS-cats show a main reduction peak at around 240-250 °C [70,73,96,111,119,171] and the reduction peak ends at around 300 °C. The reduction peak may vary depending on the crystallinity of CuPS, calcination treatment, and interaction with supports or with promoters.…”

“…Li et al [108] found that 10% of Cu showed the best performance for hydrogenation of ethylene carbonate (EC) to EG. Jiang et al [111] reported the 20% CuPS-cats could maximize the conversion of adipic acid (AA) and the yield of its hydrogenated product, i.e., 1,6-hexanediol (HDOL). For the conversion of furfural (FFAL) to 2-methyl furan, 25% of Cu was reported to be appropriate [106].…”

“…CuPS-cats were firstly deployed in the hydrogenation of AA to HDOL by our group [111]. CuPS-cats showed better performances in the hydrogenation of dicarboxylic than that of an impregnation-made Cu/SiO2 catalyst.…”

Determining Roles of Cu0 in the Chemosynthesis of Diols via Condensed Diester Hydrogenation on Cu/SiO2 Catalyst

“…It is noteworthy that above findings are different with those previous reported catalysis mechanism in gas-phase esters hydrogenation on copper catalyst, in which the adsorption of ester on Cu + site is always the controlling step. [5,15] Although it has been confirmed that the carbonyl group of esters can be easier adsorbed on Cu + than Cu 0 site, [16] the weak adsorption of DMA molecular on the Cu 0 surface [17] could be serious in the condensed DMA hydrogenation system. As a result of the competitive adsorption between DMA and H 2 , the adsorption of H 2 on Cu 0 site could be inhibited.…”