The interactive role of methane beyond a reactant in crude oil upgrading

Hao Xu,Zhaofei Li,Hua Song,Yimeng Li

doi:10.1038/s42004-021-00590-3

Abstract

Crude oil upgrading under methane has been reported to be an economically and environmentally promising process, while the advantageous effect of methane beyond a reactant is not fully explained. In this work, the catalytic performances, physicochemical properties and regenerability of used catalysts after crude oil upgrading under methane and nitrogen are investigated by n-butylbenzene model compound studies, catalyst characterizations and density functional theory calculations. Comparing to nitrogen, methane exhibits a protective effect on the charged catalyst despite the limited conversion, leading to better product quality and catalyst stability. This protective effect is attributed to the interaction between methane and catalytic active sites, which mainly occurs in the internal pores of the zeolitic catalyst support, resulting in unique coke distribution and inhibition of metal deposition. The interactive role of methane beyond a reactant, which is previously underestimated, is suggested to be critical for better performances of catalysts in relevant reaction processes.

Highlights

Crude oil upgrading under methane has been reported to be an economically and environmentally promising process, while the advantageous effect of methane beyond a reactant is not fully explained
The coke yield decreases dramatically, leading to almost undetectable coke formation in the third cycle. This phenomenon can be due to the fact that, coke tends to form over the fresh catalyst with abundant acid sites and wellestablished pore structures, the coking effect is remarkably inhibited over used catalyst due to acid site coverage and pore blockage
The advantageous addition of methane in the oil upgrading process has been repeatedly confirmed in our previous studies[11,23,26], which is usually explained by the reactions between methane and oil molecules[14,18,19,20]

Summary

Introduction

Crude oil upgrading under methane has been reported to be an economically and environmentally promising process, while the advantageous effect of methane beyond a reactant is not fully explained. The catalytic performances, physicochemical properties and regenerability of used catalysts after crude oil upgrading under methane and nitrogen are investigated by n-butylbenzene model compound studies, catalyst characterizations and density functional theory calculations. Methane exhibits a protective effect on the charged catalyst despite the limited conversion, leading to better product quality and catalyst stability. Satisfactory product quality can be obtained under a hydrogen atmosphere, hydrogen is not a naturally available resource and a methane reforming process is widely needed for its production[6] This process often requires severe reaction conditions, and the consequent high cost and greenhouse gas emission lead to low profitability and environmental unfriendliness[7]. This work provides new perspectives into the role methane played in improving the quality of products and prolonging the lifetime of catalysts, which demonstrates the great potential of methane utilization beyond a reactant for various catalytic processes

Methods

Results

Conclusion