Fast and Reproducible Testing of Cu–Co-Based Catalysts Applied in the Conversion of Synthesis Gas to Ethanol and Higher Alcohols

Abstract

A test procedure for alkali-free Cu-Co-based catalysts synthesized by co-precipitation was established allowing the fast assessment and screening of their catalytic properties in the synthesis of higher alcohols by online GC analysis. Due to precisely controlled initial deactivation of the catalysts at 280°C long-term measurements were avoided and steady-state conditions at 260°C were reached within a short period of time. Temperatures up to 300°C were found to favor the formation of methanol, whereas the product distribution was not affected at lower space velocities. Even traces of alkali ions present due to insufficient washing were found to strongly affect the catalytic properties. Graphical Abstract 0 1 0 2 0 3 0 0 1 2 3 4 5 time on stream / h X CO / % 260 280 300 temperature / °C isothermal measurement at 260°C

Structure–activity relationships of Co-modified Cu/ZnO/Al2O3 catalysts applied in the synthesis of higher alcohols from synthesis gas

“…According to this hypothesis, both the reduction and the reaction conditions have to be optimized carefully to obtain high yields of higher alcohols.The catalyst exhibiting a Cu/Co ratio of 2.5 providing the best trade-off between product distribution and degree of CO conversionis currently used for further chain growth modification with alkali compounds, which are known to promote the chain growth probability. [11,19,20] …”

“…[19] The most promising catalysts were flushed with inert gas,sealed by stainless-steel valves, and transferred into a glove box avoiding re-oxidation and contamination by air and were further prepared under Ar atmosphere for characterization.…”

“…This is of major importance as alkali compounds -even as trace impurities -are known to significantly influence the catalyst properties in HAS, making a reliable and comparable interpretation of the results difficult. [11,19,20] Despite different compositions all calcined catalyst precursors have rather similar specific surface areas (Table 2), which slightly increased with increasing Co content. In similar samples containing Co,Cu andAlwithout Zn deAguinoetal.…”

Metal–support interactions in surface-modified Cu–Co catalysts applied in higher alcohol synthesis

“…2,13 Thus, uncertain amounts of alkali residues in catalyst samples prepared by conventional co-precipitation or impregnation methods can have a strong impact on the catalyst performance and cause misleading results. 30 The alkali-free Cu-Co model catalysts described in this paper were successfully applied in HAS, revealing the first insight into the role of metal-support interactions.…”

“…Online gas analysis was realized by using two isotherm operating gas chromatographs (GC, Shimadzu 14A, Shimadzu 8A) using a Porapak N column to determine light hydrocarbons, alcohols, CO 2 , and H 2 O as well as a Molsieve 5A column to determine N 2 , CO, and CH 4 . 30…”