Co/Co6Mo6C@C nanoreactors derived from ZIF-67 composite for higher alcohols synthesis

Abstract Direct production of higher alcohols from syngas provides a promising route for the conversion of methane-rich feedstocks into value-added commodity chemicals. However, the rational catalyst design for this process remains a challenge due to severe long-standing sintering problem, low dispersion of active sites and uncontrollable synergism between CO dissociation and CO insertion. Here, we demonstrate the successful development of highly active catalyst for higher alcohols production based on the confined carbonization in metal-organic framework (MOF) matrix. Starting from a compound consisting of cobalt-based MOF host (ZIF-67) and molybdenum-based polyoxometalates guest (H3PMo12O40), Co/Co6Mo6C confined in the carbon matrix is achieved with well-defined morphology and high porosity after carbonation in N2. The Co4.7Mo@C with optimal fraction of Co0 and Co6Mo6C exhibits remarkable performance for higher alcohols synthesis, with a CO conversion of 48% and C2+OH space time yield of 99 mg/gcat.h under 275 °C and 3.0 MPa. Compared to the literature, the developed Co4.7Mo@C catalyst from MOF displayed favourable higher alcohols production rates. The balance of Co0/Co6Mo6C is found to be crucial for the observed reactivity, where Co0 is for CO dissociation and C-C chain growth and Co6Mo6C is highly efficient for CO nondissociative adsorption and CO insertion. Moreover, the synthesized catalyst also displays exceptional stability in a 100 h long-term stability test owing to the uniform dispersion of active centres, demonstrating great potential for large-scale application.