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The direct hydrogenation of CO 2 to methanol is an attractive approach to employ the greenhouse gas as a chemical feedstock. However, the commercial copper catalyst, used for methanol synthesis from CO-rich syngas, suffers from deactivation at elevated CO 2 partial pressure. An emerging alternative is represented by In 2 O 3 as it withstands the hydrothermal conditions induced by the reverse water-gas shift reaction. The active sites for the adsorption of CO 2 and the subsequent conversion into methanol were shown to be oxygen vacancies on the surface of In 2 O 3 . In this study, N 2 O was utilized as a probe molecule to quantify the number of vacancies on indium oxide catalysts. The number of inserted oxygen atoms could be correlated to the respective CO 2 hydrogenation activity. Furthermore, the atomic efficiency of indium was enhanced by applying atomic layer deposition of indium oxide on ZrO 2 .

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Platinum group metal phosphides are reviewed as catalytic materials for hydroprocessing and syngas-related catalysis. Starting from synthetic procedures leading to highly disperse nano-particular compounds, their properties in the applications are discussed and compared with relevant benchmarks, if available. Regarding their mode of action, two confronting mechanistic scenarios are presented: (i) a cooperative scenario in which catalytic sites of different functionalities are active in hydroprocessing and (ii) single site catalysis, which appears to be the relevant mode of action in syngas-related catalysis and which occurs over "frustrated" active sites.

We propose a novel high-throughput workflow, combining DFTderived atomic scale interaction parameters with experimental data to identify key performance-related descriptors in CO2 to methanol reaction, for In-based catalysts. Utilizing advanced...

Background: Renewable feedstocks and bio-refinery concepts are the key to a successful transition to a sustainable chemical industry. One conceivable refinery concept is based on pyrolysis oils from biomass, though these oils are quite difficult to handle. A well investigated approach to upgrade pyrolysis oil and turn it into a valuable products is catalytic hydrodeoxygenation (HDO). However, this process has to be optimized and new ideas are needed to make the hydrodeoxygenation process attractive sustainable and economically competitive. With regard to the many successful applications of gas-expanded liquids in heterogeneous catalysis, the expansion of pyrolysis oil with carbon dioxide was applied in the context of a hydrodeoxygenation reaction. The catalyst used for HDO was Ni/Al 2 O 3 (nickel loading 20 %wt). Results:The influence of CO 2 on the viscosity was found to be quite strong at low temperature. At 52 °C and a CO 2 pressure of 0.5 MPa the viscosity is reduced by 30 %. With 4.0 MPa of CO 2 the viscosity decreases by 60 %. With supercritical CO 2 a volume expansion of 5 % was observed. The hydrodeoxygenation showed best results at 340 °C and autogenous pressure. The experiments were started at a total pressure of 8.0 MPa at room temperature (H 2 + CO 2 ), with a respective partial pressure of CO 2 of 0 MPa, 2.0 MPa or 4.0 MPa. A deoxygenation degree of around 70 % could be reached (dry basis) under each atmosphere. The analysis of the upgraded products by different techniques indicated a slight decrease of hydrogenation with increasing the pressure of CO 2 .Conclusions: Despite we observed a change in the physical properties when expanding the pyrolysis oil with CO 2 , no real improvement of the catalytic hydrodeoxygenation reaction (e.g. deoxygenation degree) could be found yet. Possible reasons for the absence of gas-expanded liquid effects could be the polar nature of the used pyrolysis oil and the high temperature. We assume that a viscous and more tar-like, but less polar pyrolysis oil will be more influenced. Gas-expansion with CO 2 tends to be less effective with polar liquids due to the unpolar nature of CO 2 . The only observed effect in our actual system was a decrease of the hydrogenation with decreasing partial pressure of hydrogen.