Abstract
Eschewing the common trend toward use of catalysts composed of Cu, it is reported that PdZn alloys are active for CO2 hydrogenation to oxygenates. It is shown that enhanced CO2 conversion is achievable through the introduction of Bronsted acid sites, which promote dehydration of methanol to dimethyl ether. We report that deposition of PdZn alloy nanoparticles onto the solid acid ZSM-5, via chemical vapor impregnation affords catalysts for the direct hydrogenation of CO2 to DME. This catalyst shows dual functionality; catalyzing both CO2 hydrogenation to methanol and its dehydration to dimethyl in a single catalyst bed, at temperatures of >270 °C. A physically mixed bed comprising 5% Pd 15% Zn/TiO2 and H-ZSM-5 shows a comparably high performance, affording a dimethyl ether synthesis rate of 546 mmol kgcat–1 h–1 at a reaction temperature of 270 °C.
Highlights
H-ZSM-5 shows a dimethyl ether synthesis rate of mmol kgcat−1 h−1 at a reaction temperature of Methanol is ubiquitous within the chemical industry, with global demand exceeding 57 Mt/annum
1730 mmol bar reaction pressure.[23]. To determine whether this catalyst could function as the CO2 hydrogenation catalyst in a mixed catalyst bed, binary composites were prepared using the solid acids: γ-Al2O3 and H-ZSM-5 (30)
dimethyl ether (DME) can be produced through either (i) direct hydrogenation of CO2 to DME or (ii) hydrogenation of CO2 to methanol with subsequent methanol dehydration
Summary
Methanol is ubiquitous within the chemical industry, with global demand exceeding 57 Mt/annum. DME is a key feedstock for production of methylating agents for organic synthesis.[2] DME has been identified as an environmentally friendly fuel, with low associated emissions of NOx, hydrocarbons, CO and SOx.[3] Through the methanol to gasoline (MTG) process, methanol is catalytically converted to yield an equilibrium mixture containing methanol, DME and water This is converted to hydrocarbons.[4] Being both exothermic and reversible, methanol dehydration is subject to thermodynamic limitation, though effectively not so under methanol synthesis conditions.[4] Integrating methanol dehydration into CO2 hydrogenation reaction systems might increase hydrogenation yields, by intercepting the methanol through dehydration to DME, shifting the reaction equilibrium toward methanol formation
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
