A tailored multi-functional catalyst for ultra-efficient styrene production under a cyclic redox scheme

Abstract

Styrene is an important commodity chemical that is highly energy and CO2 intensive to produce. We report a redox oxidative dehydrogenation (redox-ODH) strategy to efficiently produce styrene. Facilitated by a multifunctional (Ca/Mn)1−xO@KFeO2 core-shell redox catalyst which acts as (i) a heterogeneous catalyst, (ii) an oxygen separation agent, and (iii) a selective hydrogen combustion material, redox-ODH auto-thermally converts ethylbenzene to styrene with up to 97% single-pass conversion and >94% selectivity. This represents a 72% yield increase compared to commercial dehydrogenation on a relative basis, leading to 82% energy savings and 79% CO2 emission reduction. The redox catalyst is composed of a catalytically active KFeO2 shell and a (Ca/Mn)1−xO core for reversible lattice oxygen storage and donation. The lattice oxygen donation from (Ca/Mn)1−xO sacrificially stabilizes Fe3+ in the shell to maintain high catalytic activity and coke resistance. From a practical standpoint, the redox catalyst exhibits excellent long-term performance under industrially compatible conditions.

DFT study on the mechanism of simultaneous trifluoromethylation and oximation of aryl-substituted ethylene.

“…It is an important monomer of synthetic resin and an important industrial raw material to prepare ion exchange resin and synthetic rubber in industry. In addition, styrene can also be used in pharmaceutical, dyes, pesticides and mineral processing industries [55]. Trifluoromethyl is often used as a bioisostere in place of chlorine or methyl in the preparation of some derivatives.…”

Catalytic Materials: Concepts to Understand the Pathway to Implementation

“…Chemical looping is another route to overcome equilibrium in the reactor. 92,93 Reactive distillation is a well-known example where the equilibrium is broken and capital costs are saved. 94 The combination of a membrane with a catalyst also allows one to break the equilibrium.…”

“…This is, for instance, the case of the industrial styrene dehydrogenation, which is an equilibrium-limited reaction, having a large recycle loop. Significant efforts in developing an oxidative equilibrium-free styrene reaction have been put forward in the past, and in more recent years, by breaking the equilibrium with an oxidant. − This example refers to changing the chemistry from an equilibrium-limited process to an equilibrium-free process by adding an oxidant. Chemical looping is another route to overcome equilibrium in the reactor. , Reactive distillation is a well-known example where the equilibrium is broken and capital costs are saved .…”

“…Comparing the conventional reaction (steam dehydrogenation; see rxn (1) in Figure A) and the emerging one (oxidative dehydrogenation; see rxn (2) in Figure A) is complex. The conventional process is energy-intensive but highly selective to styrene, with benzene and toluene as byproducts; these byproducts have a market and commercial value. The oxidative dehydrogenation reaction does not require energy (it produces heat since it is an exothermal reaction), but it is less selective than the conventional one.…”

A First-Principles Microkinetic Rate Equation Theory for Heterogeneous Reactions: Application to Reduction of Fe2O3 in Chemical Looping

“…Chemical looping is an inherent CO 2 separation process in which the oxygen in air is transferred to fuel by using an oxygen carrier. − The oxygen carrier is solid particles that circulate between the air reactor and fuel reactor and is oxidized by oxygen in the air reactor and reduced by fuel in the fuel reactor. The chemical looping concept (CLC) can be applied in many heterogeneous catalytic processes, such as chemical products generation by the chemical looping selective oxidation and CO 2 reduction and utilization by the reverse water–gas shift chemical looping . Fe-based materials are widely used as an oxygen carrier in chemical looping because of their inexpensiveness and large reserves. − Ilmenite has been used in different scale chemical looping units such as 10 kW th , 30 kW th , 50 kW th , 100 kW th , and 1 MW th chemical looping pilots and demonstrated its acceptable reactivity, good stability, and low attrition rate.…”