Research Hotspots and Developing Trends on Hydrothermal Conversion of Waste Biomass: Based on CiteSpace Analysis for the Knowledge Mapping

The ecological safety has been the focus and difficulty in management of waste biomass by reduction and recycling modes. In recent years, hydrothermal conversion technology has been developed rapidly, which is suitable for the treatment of waste biomass with high moisture content. In addition, it has great potential for the harmless treatment and high value-added utilization of waste biomass. In this study, 2 960 literatures were used as the data source, including 600 and 2 360 from CNKI and Web of Science databases, respectively, from January 2000 to December 2019. CiteSpace knowledge mapping software 5.5 was used to analyze authors, institutions and key words derived from the data source. Then the hot spots and development trend of this technology were analyzed based on the key words cluster analysis method. The results show that in terms of the global number of literatures on hydrothermal conversion of waste biomass, there were three stages between 2000 and 2019, including slow growth period (from 2000 to 2007), rapid growth period (from 2008 to 2016), and slight decline period (from 2017 to 2019). In the past two decades, among all the literatures the Chinese and English literatures associated with hydrothermal conversion of agricultural waste biomass kept growing. Chinese scholars have made outstanding contributions to the study of hydrothermal conversion of waste biomass. The research hotspots were focused on the production and properties of solid products (especially carbon-based materials) and liquid products (especially bio-oil). It is predicted that the developing trend of this technology will concentrate on the pretreatment of raw materials, technological conditions, reaction process, and the high value-added utilization of products. This study could provide references for the industrial development of hydrothermal conversion technology used in the field of ecological and safe treatment of waste biomass.