How the biodiesel from immobilized enzymes production is going on: An advanced bibliometric evaluation of global research

The production of biodiesel through enzymatic routes has attracted significant attention, mainly because this can be regarded as a “green route” for the manufacture of fuels. In this way, an advanced bibliometric analysis comprising the global scientific production of biodiesel through immobilized enzymes was conducted. Thus, 923 papers were retrieved, analyzed, and classified according to the reported substrates, enzymes, supports, immobilization procedures, and reactors. Researchers from 748 institutions of 64 distinct countries authored the analyzed articles, showing the widespread interest in these technologies, although 10 countries concentrate more than 80% of the total number of documents published in this area, including China (23%), Brazil (17%), and India (11%). Particularly, most papers reported the use of vegetable oils (67%) as raw materials. In the last decade, approximately 80% of the published research focused on the use of supports to manufacture immobilized and insoluble biocatalysts. Enzymes have been obtained mostly from fungal sources (64%), especially lipases produced by Thermomyces lanuginosus (14.4%). Among the available commercial immobilized biocatalysts, Novozym 435 is certainly the one cited most frequently (55.9%) followed by Lipozyme RM IM (13.7%) and Lipozyme TL IM (16.7%). Additionally, the majority of the manuscripts reported the use of stirred tank reactors (83.0%) to perform the enzymatic reactions. Based on the surveyed literature, research trends indicate that new technologies are being developed to turn the enzymatic production of biodiesel more sustainable and economically viable, based mainly on the use of more active biocatalysts, more sustainable enzyme supports, and low-cost residues as raw materials.