Syngas to light olefins conversion with high olefin/paraffin ratio using ZnCrOx/AlPO-18 bifunctional catalysts

Abstract

Direct synthesis of light olefins from syngas (STO) using a bifunctional catalyst composed of oxide and zeolite has attracted extensive attention in both academia and industry. It is highly desirable to develop robust catalysts that could enhance the CO conversion while simultaneously maintain high selectivity to C2-C4 olefins. Herein, we report a bifunctional catalyst consisting of ZnCr binary oxide (ZnCrOx) and low-Si AlPO-18 zeolite, showing both satisfying selectivity to C2-C4 olefins of 45.0% (86.7%, CO2 free) and high olefin/paraffin ratio of 29.9 at the CO conversion of 25.2% under mild reaction conditions (4.0 MPa, 390 °C). By optimizing the reaction conditions, the CO conversion could be markedly increased to 49.3% with a slight drop in selectivity. CD3CN/CO-FTIR characterizations and theoretical calculations demonstrate that low-Si AlPO-18 zeolite has lower acid strength, and is therefore less reactive toward the hydride transfer in the STO reaction, leading to a higher olefin/paraffin ratio.

Design of a core–shell catalyst: an effective strategy for suppressing side reactions in syngas for direct selective conversion to light olefins

“…[21][22][23][24][25][26][27][28][29] For the above-mentioned ndings, a new direct route for syngas to light olen (STO) synthesis using physical mixture catalysts has been reported. [30][31][32][33][34][35][36] The light olen selectivity breaks through the Anderson-Schulz-Flory distribution, which is beyond 58%. Even though it is a discovery of great importance, the challenges of suppressing highly undesirable CO 2 selectivity of approximately 50% and uneven mixing of physical mixture catalysts still need to be optimized for its further use in industrialization.…”

Relay catalysis in the direct conversion of carbon dioxide to high-value chemicals

“…SAPO分子筛作为双功能催化剂的MTH组分时, 催化 剂有可能在更苛刻的反应条件下获得高催化活性和高 产物选择性 [103,104] . 分子筛催化剂的形貌及其与复合氧化物的耦合方 式(接触距离)显著影响双功能催化剂性能.…”

A Metal‐Segregation Approach to Generate CoMn Alloy for Enhanced Photothermal Conversion of Syngas to Light Olefins

“…[ 12 ] In addition, He and co‐workers developed a bifunctional catalyst consisting of ZnCr binary oxide (ZnCrO x ) and low‐Si AlPO‐18 zeolite, showing both satisfying selectivity to C 2 − 4 = of 45.0% and high olefin/paraffin ratio (abbreviated as o/p) of 29.9 at the CO conversion of 25.2%. [ 13 ] In the above‐mentioned works, the selectivity of by‐product CO 2 is relatively high; the source of CO 2 mainly comes from water–gas shift (WGS) reaction, because most of carbide‐ and oxide‐based catalysts are also active for the WGS reaction. [ 14 ] The large amount of CO 2 produced in the FTS reactor not only causes low‐effective utilization of carbon resources but also consumes additional energy for heating, compression, and separation, and even affects product selectivity.…”