Hydrogenolysis of Glycerol to Propylene Glycol: Energy, Tech-Economic, and Environmental Studies.

Puhua Sun,Zhichao Zhang,Wenjuan Yan,Chaohe Yang,Dongpei Zhang,Jie Zhang,Ziyuan Liu,Mengyuan Liu,Ningkun Xu,Guangyu Zhang,Wenxiang Zhang,Xiao Yu,Xin Jin

doi:10.3389/fchem.2021.778579

Abstract

Hydrogenolysis of glycerol to propylene glycol represents one of the most promising technologies for biomass conversion to chemicals. However, conventional hydrogenolysis processes are often carried out under harsh H2 pressures and temperatures, leading to intensive energy demands, fast catalyst deactivation, and potential safety risks during H2 handling. Catalytic transfer hydrogenolysis (CTH) displays high energy and atom efficiency. We have studied a series novel solid catalysts for CTH of glycerol. In this work, detailed studies have been conducted on energy optimization, tech-economic analysis, and environmental impact for both processes. The key finding is that relatively less energy demands and capital investment are required for CTH process. CO2 emission per production of propylene glycol is much lower in the case of transfer hydrogenolysis. The outcome of this study could provide useful information for process design and implementation of novel hydrogenolysis technologies for other energy and environmental applications.

Highlights

Aqueous phase hydrogenolysis of bio-oxygenates provides a most promising technology for the production of various megaton chemicals from renewable feedstocks. (Wang et al, 2015a; Jin et al, 2019a; Park et al, 2021)
The key finding in this part is that total energy input for Catalytic transfer hydrogenolysis (CTH) of glycerol is approximately 83% of conventional hydrogenolysis (CHDO) process
Detailed economic analysis has demonstrated a total reduction of 7% for total investment in CTH scheme, owing to simplification of H2 handling equipment

Summary

Introduction

Aqueous phase hydrogenolysis of bio-oxygenates provides a most promising technology for the production of various megaton chemicals from renewable feedstocks. (Wang et al, 2015a; Jin et al, 2019a; Park et al, 2021). Hydrogenolysis of glycerol, a bio-diesel by-product, can produce propylene glycol (PG), 1,3-propanediol, ethylene glycol (EG), as well as propanols for many downstream applications such as anti-freezes, polyesters, pharmaceuticals, and solvents. This is one of the most popular subjects which is under extensive studies in both academia and industry. Hydrogenolysis of glycerol is often conducted under elevated temperatures and H2 pressures (>230°C, >4 MPa). This process is still heavily dependent on the use of fossil-derived H2, with cost-ineffective investment on H2 compression, recycling, and manufacture of process equipment. One should note that most hydrogenation plants have to be established adjacent to H2

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