Production of biodiesel under supercritical conditions: State of the art and bibliometric analysis

The demand for biodiesel as an alternative and potentially renewable fuel is constantly rising. Biodiesel production from lipids in supercritical conditions offers several advantages over other catalytic processes. These advantages include high-efficiency production, environmental friendliness and the possibility of using a broad range of feedstock sources. As a consequence, there is a great interest in biodiesel production research using supercritical fluids as a sustainable technology option. In this sense, bibliometric reviews can be very useful for the interpretation of scientific production and research trends in this field. Thus, this work presents a scientometric study on biodiesel production research under supercritical conditions from 2001 to 2019, based on the Web of Science (c) database. 608 articles were analyzed and the parameters considered were: (i) publication type, language and output characteristics, (ii) Lotka's Law, Price's index and h-index, (iii) authors, countries and institutions collaboration analysis, (iv) publication performance by authors, journals, institutions and countries and (v) author keywords, single title words and keywords Plus analysis. The productivity patterns of authors, journals, institutions and authors keywords were found to fit Lotka's law. In terms of feedstock used in supercritical conditions, the bibliometric analysis showed a clear transition from first- to third-generation biodiesel, with special attention paid to the experimental study of supercritical reaction conditions. By contrast, further process optimization, the reduction of the severity of the supercritical conditions through devised strategies to lower energy consumption and further economic analysis are still needed, among other factors, for the real implementation of the technology.