Galvanic Deposition of Au on Paperlike Cu Fiber for High‐Efficiency, Low‐Temperature Gas‐Phase Oxidation of Alcohols

Abstract

The highly active and selective gold-on-copper fiber catalysts with excellent heat conductivity were successfully prepared for high-efficiency gas-phase selective oxidation of various alcohols. The Au/Cu-fiber catalysts were obtained by conducting galvanic deposition of Au onto a thin-sheet microfibrous structure that consisted of 5 vol % Cu-fiber (8 mm diameter), and 95 vol % voidage. The best catalyst was Au-3/Cu-fiber-200 (Au loading: 3 wt %; calcined at 200 8C in air), which was effective for acyclic, benzylic, and polynary alcohols using a high weight hourly space velocity of 20 h À1 . Benzyl alcohol conversion of 86 % was obtained with 99 % selectivity to benzaldehyde at 220 8C. Cyclopropanemethanol could be transformed to cyclopropanecarboxaldehyde, with conversion of 91 % and selectivity of 95 % at 250 8C. 1,2-Propanediol demonstrated a high con-

Galvanic deposition of silver on 80‐μm‐Cu‐fiber for gas‐phase oxidation of alcohols

“…With increasing O 2 /ol from 0.4 to 0.6 and then up to 1.2, the benzyl alcohol conversion was increased to 94% and then slowly decreased down to 89% while the selectivity to benzaldehyde remained almost unchanged. Similarly with the previously reported catalysts of Au/Ni‐fiber and Au/Cu‐fiber, the Ag‐10/80‐Cu‐fiber‐400 catalyst showed an excellent ability of selective oxidation rather than deep oxidation even in an O 2 ‐rich atmosphere. On the balance between benzyl alcohol conversion and O 2 utilization efficiency, the optimal O 2 /ol ratio was set as 0.6.…”

“…As previously noted on the Au/Cu‐fiber catalyst, the AuCu(alloy)‐Cu 2 O active composites are formed during the alcohol oxidation reaction and provide a synergistic effect, thereby leading to a dramatic improvement in the catalytic activity. For the Ag‐10/80‐Cu‐fiber‐400 catalyst, is there a similar synergistic interaction between Ag and Cu 2 O?…”

“…For the gas‐phase selective oxidation of alcohols, we have developed several catalysts using the sinter‐locked metal‐microfiber (8 μm in dia.) as supports, such as Ag/Ni‐fiber, Au/Ni‐fiber, and Au/Cu‐fiber catalysts. During the long‐time test of the oxidation of benzyl alcohol over the Ag/Ni‐fiber and Au/Ni‐fiber catalysts, carbide of Ni x C comes into being as poison and deactivates the catalyst activity .…”

Microfibrous entrapment of Ni/Al2O3 for dry reforming of methane: Heat/mass transfer enhancement towards carbon resistance and conversion promotion

“…Recently, Sheng et al [18] studied the heat transfer characteristics of the MFEC, and noted that the effective thermal conductivity of Cu-MFEC is nearly 10 times of that of Al 2 O 3 PB, and therefore provided better performance for FischereTropsch synthesis. Zhao et al [20,28,29] reported a new-type microfibrous structured Au catalysts for strongly exothermic gas-phase alcohol oxidation processes, demonstrating a very low temperature difference (DT: w10 K) between the bed and reactor external wall due to the excellent bed thermal conductivity. In contrast, a very high DT of w53 K was observed over AueCu/SiO 2 catalysts for the oxidation of benzyl alcohol because of their poor thermal conductivity [29].…”

High-performance SS-fiber@HZSM-5 core–shell catalyst for methanol-to-propylene: A kinetic and modeling study

“…Recently, microfibrous structured catalysts and reactors (MSCRs), as one primary kind of structured catalysts or catalytic reactors (SCRs), have been developed and applied in order to achieve the aim of process intensification in chemical industry, because MSCRs and other SCRs can be precisely designed in full detail up to the local surroundings of the catalyst, and the exact shape and size of all column internals are determined by pre-design and calculation rather than trial and error [35,36]. Therefore, these MSCRs exhibit great flexibility with respect to different length scales (e.g., diffusion lengths and voidage) and allow exceptionally large rates and selectivities [36,37], and have many significant functional advantages over the conventional catalysts and reactors, providing broad prospects in desulfuration [38,39], air filtration [40,41], H 2 fuel generation and cleanup [42][43][44][45], selective oxidation [46][47][48][49][50][51][52] and other fields [53][54][55][56], especially providing a new way of designing efficient catalysts and reactors for mass and/or heat transfer limited reactions [57]. In our previous studies [16,58], a new standing-free microfibrous-structured ZSM-5 zeolite catalyst was developed, being obtainable in a macroscopic scale by direct growth of the ZSM-5 zeolite crystals onto a three-dimensional (3D) porous network of sinter-locked metal microfibers.…”