Ultrathin Metal–Organic Framework Nanosheets for Selective Photocatalytic C2H2 Semihydrogenation in Aqueous Solution.

The selective semihydrogenation of C2H2 to C2H4 in crude C2H4 (with ~1 vol % C2H2 contamination) is a crucial process in the manufacture of polyethylene. Comparing to conventional thermalcatalytic route with Pd as catalyst under high temperature with H2 as hydrogen source, photocatalytic C2H2 reduction reaction with H2O as hydrogen source can achieve high selectivity under milder conditions, but has rarely been reported. Here, we present a kind of ultrathin metal–organic framework nanosheets (Cu‐Co‐MNSs) that demonstrate excellent catalytic activities in the semihydrogenation of C2H2. Employing Ru(bpy)32+ as the photosensitizer, this catalyst attains a noteworthy turnover number (TON) of 2124 for C2H4, coupled with an impressive selectivity of 99.5 % after 12 h visible light irradiation. This performance is comparable to molecular catalysts and notably surpasses the efficiency of bulk metal–organic framework materials. Furthermore, Cu‐Co‐MNSs achieve a 99.95 % conversion of C2H2 under industrial relevant conditions (1.10 % C2H2 in C2H4) with 90.3 % selectivity for C2H4 over C2H6, demonstrating a great potential for polymer‐grade C2H4 production. [ABSTRACT FROM AUTHOR]