Selective Production of Aromatics Directly from Carbon Dioxide Hydrogenation

Abstract

Conversion of carbon dioxide (CO 2 ) to fuels and chemicals with the help of renewable hydrogen (H 2 ) is a very attractive approach to reduce CO 2 emissions and replace dwindling fossil fuels. However, it is still a great challenge to synthesize aromatics directly from CO 2 hydrogenation, because CO 2 is thermodynamically very stable, and the aromatics are highly unsaturated products with complex structures. Here, we demonstrate that the combination of the sodium-modified spinel oxide ZnFeO x , which alone shows excellent performance for CO 2 hydrogenation to olefins, and hierarchical nanocrystalline HZSM-5 aggregates can realize a highly efficient synthesis of aromatics directly from CO 2 and H 2 . The maximum of aromatics selectivity was up to 75.6% among all hydrocarbons at 41.2% CO 2 conversion. Additionally, the selectivity toward CO and CH 4 is usually less than 20% over this catalyst system. The suitable amount of the residual sodium, hierarchical pore structure, and appropriate density of Brønsted acid sites endow the composite catalyst with an outstanding aromatics yield and high catalytic stability.

Novel Heterogeneous Catalysts for CO2 Hydrogenation to Liquid Fuels

“… Detail hydrocarbon product distribution obtained over (A) well-defined mesoporous carbon (MPC) supported Fe–K in the range of C 15–27 , 95 (B) Fe–Cu, 98 (C) Na–Fe 3 O 4 (middle), 105 Na–Fe 3 O 4 /HZMS-5 (left), 105 and Na–Fe 3 O 4 /HMCM-22 (right), 109 (D) ZnFeO x -4.25Na (left) and ZnFeO x -4.25Na/HZSM-5 (right) under the reaction conditions of 320 °C, 3.0 MPa, H 2 /CO 2 = 3, and 4000 mL g –1 h –1 , 107 as well as (E) FeK1.5/HSG|HZSM-5 (SiO 2 /Al 2 O 3 molar ratio of HZSM-5 = 50) catalysts during the CO 2 hydrogenation reaction. 110 Reprinted with permission from refs ( 95 ), ( 98 ), ( 105 ), ( 107 ) , ( 109 ), and ( 110 ). Copyright 2017 and 2020 Elsevier, Copyright 2017 Springer-Nature, and Copyright 2018 and 2019 American Chemical Society.…”

Synthesis of monocarboxylic acids via direct CO2 conversion over Ni–Zn alloy catalysts

“…Consequently, high space time yields (STYs) of 0.405 and 0.125 mmol g − 1 h − 1 were achieved for AA and PA, respectively (Supplementary Table 1). Although numerous reports have been published on the direct hydrogenation of CO 2 to methanol 5,[42][43][44][45] , C 5+ liquid hydrocarbons [46][47][48][49][50] , and aromatics 19,20,[51][52][53] , studies dedicated to the direct CO 2 conversion to monocarboxylic acids have been extremely rare. A single article, which described the possibility of forming AA over a Ag-promoted Rh/SiO 2 catalyst, was published in the early 1990s 34 ; however, the reported production rate of AA was very low (~ 0.035 mmol g − 1 h − 1 ).…”

Selective Conversion of CO2 into para‐Xylene over a ZnCr2O4‐ZSM‐5 Catalyst

“…Generally, the hydrogenation of CO 2 to olefins or aromatics proceeds through two different routes: direct Fischer–Tropsch synthesis (FTS) route and indirect methanol route [3] . For the FTS route, CO 2 is firstly transformed to CO via reverse water‐gas shift (RWGS) reaction with simultaneously catalyzing conversion of CO into hydrocarbons by the typical Fischer‐Tropsch mechanism [4] . However, the produced olefins/aromatics obey the traditional Anderson‐Schulz‐Flory (ASF) distribution with very low selectivity.…”