Oxygenated compounds, such as ethanol, ethylene glycol, organic carbonates, are attractive commercial products because of their versatile applications in fuel additives, polymers, etc. In order to meet the future demand, a wide application of routes starting from syngas is appealing since coal, natural gas, biomass and even CO2 could be utilised for production of this feedstock. In these routes, ester hydrogenation is one of the key steps, where Cu-based catalsyts are used accounting for its excellent activity and selectivity on C-O/C=O bonds hydrogenolysis. In the literature, it is proposed a syngery effect of Cu0 and Cu+ species could remarkably enhance the catalytic performance. However, under the reaction conditions of high temperature and abundant hydrogen atmosphere, neither of them is easily to maintain. We developed an ammonia evaporation hydrothermal method to produce lamella-structured copper silicate catalysts with stable and coexisting Cu0 and Cu+ active sites and found the selectivity of ethanol or ethylene glycol can be tuned simply by regulating the reaction temperature. The technology is successfully applied in the large-scale catalyst preparation. And the obtained catalysts display excellent activity, selectivity and stability in thousands t/a pilot plant trial for 7000 h, which reaches the requirements for industrial applications. We also proposed there was a balancing effect between the Cu0 and Cu+ species in their synergetic catalysis and illuminated their roles in reaction by both experimental and theoretical investigations. Furthermore, a core-sheath Cu@copper-silicate nanotube catalyst was fabricated, which exhibited remarkable stability in ester hydrogenation. It is suggested that manipulating the length of the nanotube could allow us to control the selectivity and distribution of products. Recently, we found the H2/ester ratio in feed can be decreased from 80 to 20 by using a copper silicate nanotube-assembled hollow sphere nanoreactor as catalyst, which is useful in industry practice for significantly reducing the circulation of H2 and decreasing the costs on device and energy consumption.

Nano-structured Cu-based catalysts for efficient conversion of syngas to oxygenated compounds

2019 Spring National Meeting

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