A Systematic Review of Syngas Bioconversion to Value-Added Products from 2012 to 2022

Synthesis gas (syngas) fermentation is a biological carbon fixation process through which carboxydotrophic acetogenic bacteria convert CO, CO2, and H-2 into platform chemicals. To obtain an accurate overview of the syngas fermentation research and innovation from 2012 to 2022, a systematic search was performed on Web of Science and The Lens, focusing on academic publications and patents that were published or granted during this period. Overall, the research focus was centered on process optimization, the genetic manipulation of microorganisms, and bioreactor design, in order to increase the plethora of fermentation products and expand their possible applications. Most of the published research was initially funded and developed in the United States of America. However, over the years, European countries have become the major contributors to syngas fermentation research, followed by China. Syngas fermentation seems to be developing at "two-speeds", with a small number of companies controlling the technology that is needed for large-scale applications, while academia still focuses on low technology readiness level (TRL) research. This systematic review also showed that the fermentation of raw syngas, the effects of syngas impurities on acetogen viability and product distribution, and the process integration of gasification and fermentation are currently underdeveloped research topics, in which an investment is needed to achieve technological breakthroughs.