Selective conversion of CO2 to isobutane-enriched C4 alkanes over InZrOx-Beta composite catalyst

Abstract

Direct conversion of CO2 to a single specific hydrocarbon with high selectivity is extremely attractive but very challenging. Herein, by employing an InZrOx-Beta composite catalyst in the CO2 hydrogenation, a high selectivity of 53.4% to butane is achieved in hydrocarbons (CO free) under 315 °C and 3.0 MPa, at a CO2 conversion of 20.4%. Various characterizations and DFT calculation reveal that the generation of methanol-related intermediates by CO2 hydrogenation is closely related to the surface oxygen vacancies of InZrOx, which can be tuned through modulating the preparation methods. In contrast, the three-dimensional 12-ring channels of H-Beta conduces to forming higher methylbenzenes and methylnaphthalenes containing isopropyl side-chain, which favors the transformation of methanol-related intermediates to butane through alkyl side-chain elimination and subsequent methylation and hydrogenation. Moreover, the catalytic stability of InZrOx-Beta in the CO2 hydrogenation is considerably improved by a surface silica protection strategy which can effectively inhibit the indium migration.

Restructuring Surface Lewis Pairs of FAU Zeolite through N Doping for Boosting the Toluene Side-Chain Alkylation Performance

“…All of the NMR experiments were carried out on a Bruker AVANCE-III 500 MHz spectrometer (11.7 T) operating at a Larmor frequency of 130.4 and 99.4 MHz for the 27 Al and 29 Si nuclei, respectively. A 4 mm MAS NMR probe was used to approach the 27 Al and 29 Si single-pulse experiments.…”

“…All of the NMR experiments were carried out on a Bruker AVANCE-III 500 MHz spectrometer (11.7 T) operating at a Larmor frequency of 130.4 and 99.4 MHz for the 27 Al and 29 Si nuclei, respectively. A 4 mm MAS NMR probe was used to approach the 27 Al and 29 Si single-pulse experiments. The 27 Al MAS NMR spectra were recorded by using a single-pulse sequence with a pulse length of 0.26 μs (π/12) and a recycle delay of 1 s. Chemical shifts were referenced to those of (NH 4 )Al(SO 4 ) 2 •12H 2 O at −0.4 ppm.…”

“…A 4 mm MAS NMR probe was used to approach the 27 Al and 29 Si single-pulse experiments. The 27 Al MAS NMR spectra were recorded by using a single-pulse sequence with a pulse length of 0.26 μs (π/12) and a recycle delay of 1 s. Chemical shifts were referenced to those of (NH 4 )Al(SO 4 ) 2 •12H 2 O at −0.4 ppm. The 29 Si MAS NMR spectra were recorded using high-power proton decoupling with a π/2 pulse width of 3.9 μs and a recycle delay of 80 s. The chemical shifts were referenced to Kaolinite at −91.5 ppm.…”

“…In addition, SEM images show that the size distribution and morphologies of all samples are similar, which means that the samples are mainly composed of crystallites of 2−3 μm (Figure S7). Solid-state MAS 27 Al and 29 Si NMR spectra are used to investigate the local atomic coordination environments of the catalysts. As can be seen in the 29 Si MAS NMR spectra (Figure 3a), both CsX-P and CsX-BN-600 samples exhibit four main resonances, corresponding Q 4 Si species coordinated with n OAl bonds (where n = 0, 1, 2, and 3).…”

Selective Conversion of CO2 to Trimethylbenzene and Ethene by Hydrogenation over a Bifunctional ZnCrOx/H-ZSM-5 Composite Catalyst

“…Although the tandem CO 2 hydrogenation over an OX-ZEO catalyst can acquire a relatively narrowed spectrum of hydrocarbon products with high selectivity, it is still rather challenging to get a specific hydrocarbon. Nonetheless, through selecting a proper framework of the zeotype moiety and elaborately regulating its acidity (including the strength, density, and location of acid sites) and morphology as well as combining with a matching oxide moiety, a variety of hydrocarbon products, such as ethene, propane, and butane, can be obtained with very high selectivity. − Wang and co-workers observed that owing to the synergy between Cr 2 O 3 and H-ZSM-5, a selectivity of about 76% to aromatics was obtained for the CO 2 hydrogenation over the Cr 2 O 3 /H-ZSM-5 composite catalyst at a CO 2 conversion of 34.5% . Moreover, the fraction of benzene, toluene, and xylene (BTX) in aromatics could be greatly elevated through using a modified Cr 2 O 3 /H-ZSM-5@S-1 catalyst, where the neutralization of acid sites at the outer surface of H-ZSM-5 by S-1 (silicalite-1) on the core–shell structured H-ZSM-5@S-1 could precisely suppress the isomerization and other side reactions.…”