Cu(II)Cu(I)/activated carbon (AC) catalysts with different copper chloride and cuprous chloride impregnation orders were prepared. The effect of the Cu(II) additive on the catalytic performance of Cu(I)/AC catalysts for gas−solid acetylene dimerization was evaluated. The optimal catalytic performance was obtained using the Cu(II)0.3Cu(I)1/AC catalyst with an average acetylene conversion of 70.0%. This value was an increase of 33.0% compared to the average acetylene conversion of 37.0% (Cu(I)1/AC) under the same reaction conditions. The results from the characterization of the Cu(II)Cu(I)/AC catalysts demonstrated that the addition of Cu(II) increased the dispersion of copper and inhibited copper loss on the catalysts. Consequently, our findings indicate that a suitable Cu + /Cu 2+ molar ratio improves the catalytic performance and stability.

A gas–solid acetylene dimerization over copper-based catalysts, with high acetylene conversion and MVA selectivity and convenient operation, was reported.

Chemical engineering optimization from a batch process to continuous flow in liquid-phase hydrogenation brings a significant improvement in efficiency. However, its further application is limited due to the severe pressure drop and tube blockage problems in a powder-form catalyst fixed-bed reactor, especially for nanocarbon-supported catalysts. In this work, spherical monoliths containing oxygenated carbon nanotube (oCNT)-supported Pd nanoparticles (ca. average size of 2 mm) are fabricated via an in situ gelation method and applied for cinnamaldehyde (CAL) selective hydrogenation in a continuousflow system. The simulated results by the computational fluid dynamics−discrete element method (CFD−DEM) coupled method show that the pressure drop of the monolith catalyst bed is maintained within 0.4 Pa. The Pd/oCNT monolithic catalyst exhibits excellent CAL conversion of 85.8% and hydrocinnamaldehyde (HCAL) selectivity of 93.5% within a high weight hourly space velocity (WHSV) of 0.012 s −1 at mild reaction conditions (30 °C, 3 bar). The catalyst maintains robust catalytic activity and HCAL selectivity (>93%) under varied reaction temperatures (30/60 °C), H 2 partial pressures (3−10 bar), and WHSVs (0.012−0.184 s −1 ) and a stable reaction activity for more than 60 h time on stream, revealing the possibility in industrial hydrogenation reactions. The catalytic activity of the monolithic catalyst is determined by the surface properties of the carbon nanotubes and the chemical interactions between Pd nanoparticles and supports. The oxygenated functional groups and surface defects on oCNTs are beneficial for strong chemical interaction with Pd species, which forms abundant electron-deficient Pd δ+ species to facilitate C�C hydrogenation. This study puts forward insights into and perspectives for selective hydrogenation reactions in both electronic structure tuning of the active phase at the atomic scale and fabrication of monolithic catalysts at the macroscopic scale.