Highly selective synthesis of LPG from CO2 hydrogenation over bifunctional catalysts comprising modified methanol synthesis catalyst and hydrophobic zeolite DEADLINE EXTENDED TO 31/01

Academic Supervisor: Dr Nancy Artioli

Industrial supervisor: Dr Keith Simons

Context:

CO₂ hydrogenation is an effective measure for the reduction of CO₂ emission and the production of carbon compounds free from fossil fuels. In a variety of methods for CO₂ hydrogenation, a composite catalyst comprised of methanol synthesis catalyst and zeolite is regarded as a promising catalytic system for the selective production of C2+ hydrocarbons such as LPG, naphtha and gasoline. 

In these composite catalysts, a methanol synthesis catalyst and a zeolite catalyst are physically mixed to aim that methanol synthesis from CO₂ and methanol conversion to C2+ hydrocarbons progress simultaneously in a single catalytic bed. In general, methanol formation by CO₂ hydrogenation strongly depended on reaction pressure. In the composite catalyst, immediate conversion of methanol to C2+ hydrocarbons shifts the equilibrium to remove the thermodynamic limitation. Therefore, in principle, the production of C2+ hydrocarbons over the equilibrium conversion of CO₂ to methanol is possible even under a pressure of 1 MPa. However, as reported in recent papers, the yield of C2+ hydrocarbons becomes poor in usual composite catalysts using a single reactor. 

The slow methanol conversion over zeolite results in poor yield because of the predominant decomposition of methanol to CO. Since the acidity of zeolite is damaged by steam during catalytic reactions, the deactivation of acid sites on the zeolite progress by a large amount by the water produced during CO₂ hydrogenation. Since this water is not removable, new improvements are required for the composite catalyst that produces C2+ hydrocarbons in high yield from CO₂. 

Within this project, we propose to develop dual-function composite catalysts which efficiently catalyse both the suppression of methanol decomposition to CO and the prominent methanol conversion into C2+ hydrocarbons to achieve high yield. 

This can be accomplished by designing hybrid catalysts comprising a Cu-ZnO-based methanol synthesis catalyst and a hydrophobic modified zeolite, as the dehydration function. 

To attain monodispersed Cu-ZnO catalysts, we will employ a novel approach, based on ionic liquids, which can dissolve precursors, and at the same time provides a non-aqueous, non-volatile environment consisting of a dense and tuneable network of hydrogen bonds, in addition to Coulombic interactions that stabilise charge. The nanoparticles produced by this method will have higher surface area and hence higher activity than the ones synthetized by conventional precipitation methods. The copper/zinc catalysts will be then combined with different types of hydrophobic modified zeolites (mordenite, ZSM–5, HB) to further hydrogenate methanol or DME intermediates to hydrocarbon products over the zeolite acid sites.

The hydrophobic modification of zeolites, necessary to improve their catalytic performance and stability in water, will be obtained by the grafting of organo–disilane compounds like 1,4-bis(hydroxydimethylsilyl) benzene to zeolites, which produce strong bonds with the surface by the two silanols. The full coverage of the exterior surface will turn zeolites from hydrophilic to hydrophobic, improving the catalytic activity of the corresponding composite catalyst (Applied Catalysis B: Environmental 179 (2015) 37–43).

Aim of project/expected outcome:

1.   Development of an Ionic liquid synthesis method for the preparation of hybrid catalysts for a single-step synthesis of LPG (propane and butane) from CO₂

2.   Evaluation of the effect of dopant in the one-pot ionic liquid-based synthesis in order to achieve higher activity and stability compared to a commercial CuO-ZnO-Al₂O₃ catalyst. 

3.   Development of a surface-modification of zeolites with different acidity (mordenite, ZSM–5, HB) by the grafting of organo–disilane compounds to study the effect of the acidity on the C2+ selectivity.

4.   Optimize the reaction conditions (T, P, GHSV) to maximize the yield to propane and butane

1.   Determine the nature of the active sites under reaction conditions 

2.   Gain knowledge in the of the bifunctional catalyst deactivation mechanisms with T.o.S. and the presence of water

APPLICATION

You can apply for this position by filling the form at the following link:

https://esse3.unibs.it/AddressBook/ABStartProcessoRegAction.do;jsessionid=582E1CB682F71DE7A4AEB8DE027C810C.esse3-unibs-prod-01?cod_lingua=eng

In your application you need to select the specific project you are applying for: PhD program in Civil and Environmental Engineering, International Cooperation and Mathematics, Project: Highly selective synthesis of LPG from CO2 hydrogenation over bifunctional catalysts comprising modified methanol synthesis catalyst and hydrophobic zeolite

Complete information about the call and the application are available on the Univesity of Brescia website:

https://www.unibs.it/sites/default/files/2022-12/Call-PhD%20AdditPosts%20XXXVIII%20DEF.pdf

https://www.unibs.it/en/university/work-us/calls-and-notices/call-admission-phd-programmes-additional-posts-xxxviii-cycle-ay-20222023