Catalytic and Kinetic Study of the CO₂ Hydrogenation Reaction over a Fe–K/Al₂O₃ Catalyst toward Liquid and Gaseous Hydrocarbon Production

Abstract

CO2 hydrogenation toward gaseous and liquid hydrocarbons has been experimentally studied over a Fe–K/Al2O3 catalyst in a fixed-bed reactor. At 15 bar, 300 °C, 2080 N mL/gcat/h, and H2/CO2 ratio of 3, the catalyst is able to convert CO2 to an extent of 30% and with a CO selectivity around 10%. Among hydrocarbons, linear short olefins C2–C4 are the most abundant product, but linear paraffins and alcohols are also formed and chains until 30 carbon atoms are detected. Operating parameters were varied (T between 250 and 300 °C, total pressure between 10 and 25 bar, H2/CO2 ratio between 3 and 24, and GHSV between 832 and 7059 N mL/gcat/h) in order to study their effects on the catalyst activity and selectivity. It was observed that the H2/CO2 inlet molar ratio is a very important parameter, and a large excess of H2 at the reactor inlet could lead to a significant increase of the CO2 conversion, with a minimization of the CO formation. Moreover, a semiempirical macrokinetic model for this reaction was developed. The model is able to describe with good accuracy the CO2 conversion and CO selectivity, as well as hydrocarbons distribution according to their C number and their chemical nature. The model is able to predict the experimental data within an error of 20% and with a MARR lower than 5% in the experimental domain considered.

Kinetic Analysis of CO2 Hydrogenation to Long-Chain Hydrocarbons on a Supported Iron Catalyst

“…We also assessed the model of Riedel et al (which is widely used in the literature − ) for our experimental data. The model can reproduce the data satisfactorily but strongly suffers from statistically ill behaved parameters (for details see Supporting Information).…”

“…Iglesias et al 14 adapted the model without the DH reaction, as well, but refitted the parameters for their precipitated iron catalyst. Very recently, also Panzone et al 15 adopted the Riedel model and extended it with an empirical chain growth probability model to describe the activity and product distribution of an alumina supported iron catalyst.…”

Perspective on Sorption Enhanced Bifunctional Catalysts to Produce Hydrocarbons

“…The chemical industry is one of the most significant contributors to GHG emissions due to conventional processes that rely on oil and fossil resources . A sustainable solution to maintain the chemical industry while reducing GHG emissions is using CO 2 as a potential feedstock for polymers, − chemicals, − and fuels. ,, Such a transition will use catalysts to provide a technologically practical solution for mitigating GHGs. While there are several thermo- and electro-catalytic CCU schemes, ,− the integration of heterogeneous catalysts with CO 2 -capture solid sorbents may be a viable solution capable of selectively removing CO 2 directly from air or flue gases.…”

“…Typical thermal CO 2 conversion schemes use renewable hydrogen from water electrolysis as a reductant to synthesize relevant building blocks like synthesis gas (CO, H 2 ), methane, and methanol. ,,,,,− Most research using an ICCU framework has traditionally focused on C 1 products. However, the development of ICCU that can capture and convert CO 2 to C 2 + hydrocarbons could be transformative.…”

Development and Validation of a Detailed Microkinetic Model for the CO2 Hydrogenation Reaction toward Hydrocarbons over an Fe–K/Al2O3 Catalyst

“…11−13 We previously developed a detailed macrokinetic model that is able to describe the formation of all of the main species observed as products (olefins, paraffins, and oxygenates). 14 mechanism-based kinetic model was recently developed by Brubach et al, but it includes only C 4 species as products. 15 The purpose of this work is to develop a microkinetic model that is based on a hypothesis about the reaction mechanism with the aim of understanding the formation of the different groups of products observed.…”