High‐Performance Catalysts Derived from Cupric Subcarbonate for Selective Hydrogenation of Acetylene in an Ethylene Stream

Abstract

A high‐performance base metal catalyst for acetylene selective hydrogenation was prepared from cupric subcarbonate (Cu2(OH)2CO3) by thermal treatment with an acetylene‐containing gas followed by hydrogen reduction. The characterization results revealed that the copper catalyst was composed of interstitial copper carbide (CuxC) and metal Cu, which were embedded in porous carbon matrix. The CuxC crystallites, which showed outstanding hydrogenation activity, were derived from the hydrogen reduction of copper (II) acetylide (CuC2) which was generated from the reaction between acetylene and Cu2(OH)2CO3. The Cu particles and porous carbon were generated from the unavoidable thermal decomposition of CuC2. The prepared Cu‐derived catalyst completely removed the acetylene impurity in an ethylene stream with a very low over‐hydrogenation selectivity at 110 °C and atmospheric pressure. No obvious deactivation was observed in a 180‐h test run. In the Cu‐derived catalyst, CuxC served as the catalytic site for H2 dissociation, Cu mainly functioned as the site for selective hydrogenation of acetylene, whereas the porous carbon matrix posed a steric hindrance effect on the chain growth of linear hydrocarbons so as to suppress the undesired oligomerization.

Enhanced Hydrogenation Activity over a Zn-Modified Cu-Based Catalyst in Acetylene Hydrogenation

“…The SEM images (Figure S2) demonstrated that Cu 0.8 Zn 0.2 (OH)­(T140) and Cu 0.8 Zn 0.2 (OH)­(T140-R150) were still in the nanosheet structure, suggesting that the morphology of the catalysts was not changed with the thermal treatment with acetylene followed by H 2 hydrogenation. In the XRD pattern of Cu 0.8 Zn 0.2 (OH)­(T140-R150) (Figure ), apart from the intense peaks at 2θ = 43.3, 50.4, and 74.1°, which were ascribed to the (111), (200), and (220) planes of metal Cu (PDF 04-0836), respectively, the peak at 2θ = 37.2° was identical to that of the Cu x C crystal. − In addition, the intensity of the diffraction peaks attributed to Cu x C and Cu in Cu­(OH) 2 (T140-R150) was higher than that of Cu 0.8 Zn 0.2 (OH)­(T140-R150), indicating that the addition of Zn promoted the formation of the smaller crystalline size of Cu x C and Cu (Table S1), probably due to the decreased size and enhanced dispersion of Cu­(OH) 2 . Meanwhile, three kinds of crystallites were observed in the HRTEM image of Cu 0.8 Zn 0.2 (OH)­(T140-R150) (Figure ).…”

“…In the previous work, we found that Cu x C derived from copper acetylide showed high hydrogenation activity comparable to Pd. − Additionally, for Pd-based catalysts, PdM alloy is always formed with the addition of M (where M is the second metal). However, the effect of the second metal on the structure and catalytic performance of Cu x C is still lacking of further exploration.…”

Recent research advances on catalysts for selective hydrogenation of ethyne

“…Wang et al used different precursors, including Cu(OH) 2 , 98 cupric subcarbonates, 99 and Cu 2 O nanocubes 11 to synthesize Cu-based catalysts. They demonstrated that these Cu-based catalysts were composed of Cu x C and metallic Cu nanoparticles, which were buried in the porous carbon matrix.…”

A highly active catalyst derived from CuO particles for selective hydrogenation of acetylene in large excess ethylene

“…In general, Cu catalysts exhibited good hydrogenation activity at higher temperatures (4150 1C). 9,43,44 The marked difference between CuO(T120-R150) and Cu catalyst in hydrogenation activity might be related to the new crystal phase of Cu x C. [23][24][25] It was reported that, compared with the parent metals, interstitial metal carbides were more capable of adsorbing/activating H 2 and transferring active hydrogen to the reactant molecules. 45 Fig.…”

“…Recently, our group reported a non-precious composite catalyst, containing copper carbide (Cu x C) and Cu metal, which outperformed considerably the counterpart of the Cu catalyst prepared by hydrogen reduction from the same precursors. [23][24][25] The catalysts were prepared by thermal treatment with acetylene-containing gas followed by hydrogen reduction, and the precursors included Cu 2 O, Cu(OH) 2 , and Cu 2 (OH) 2 CO 3 .…”