Review of Advances in the Utilization of Biochar-Derived Catalysts for Biodiesel Production

Abstract

Biochar, obtained from the thermal decomposition of different biomass sources, can be used in various scientific technologies by virtue of its distinguishing performance. Recent developments in advanced biochar synthesis methods have led to continuous growth in the literature related to bulk biochar products and synthesized biochar substrates. This review specifically summarizes the current advanced methods for the synthesis of functional biochar catalysts and applications in (trans)esterification. Herein, first the method and design of synthesized biochar substrate catalysts are briefly introduced. Second, the applications of these synthesized biochar substrate catalysts upon (trans)esterification are comprehensively discussed. Finally, the current research status and the future perspectives of the synthesized biochar substrate catalyst are presented. It is expected that this summary will provide perspectives and instructions for future work on synthesized biochar catalysts for biodiesel products.

Biochar‐based catalysts derived from biomass waste: production, characterization, and application for liquid biofuel synthesis

“…143 The transesterification of high-acid value oils could be catalyzed by acid catalysts. 144 Meanwhile, biochars could also be functionalized using basic media including NaOCH 3 , KOH, and NaOH, or by forming composites with metal oxides in some cases. 145 In these cases, alcohol (usually methanol) could be activated to generate the CH 3 O − group after the H + ion is captured at the basic sites of biochar-based catalysts.…”

“…143 Carbonized materials possessing high surface area were discovered to have the capability to bind acid groups. 144 Indeed, peanut shell pyrolyzed under the temperature of 400 °C with a surface area of 6.616 m 2 .g −1 and a sulfonic acid density of 0.837 mmol .g −1 was reported to be an efficient catalyst in producing biodiesel, 146 whereas biochar catalysts based on sugarcane bagasse yielded slightly more biodiesel (at 96%) than oil palm trunk-based biochar catalysts (at only 88.8%). 132 In addition, Correa et al 147 produced a variety of sulfonated biochars from magnolia fruit shells and used them for esterification with methanol and oleic acid.…”

“…Owing to its large specific surface area, distinctive aromatic structure, numerous electron donor functional groups appearing on the modified biochar catalyst's surface, along with low inorganic salt concentration, reed-originated biochar provided an excellent precursor for highly active solid acidic catalysts. 144 Meanwhile, Kandasamy et al 161 figured out that applying Spirulina platensis-derived biochar nanocomposites could reduce the nitrogen and oxygen concentration while increasing the heating value of its biooil to 35.64 MJ.kg −1 . Aside from that, the incorporation of the in situ biochar nanocomposite boosted energy recovery by up to 65.34%.…”

“…3(a) 143 . The transesterification of high‐acid value oils could be catalyzed by acid catalysts 144 . Meanwhile, biochars could also be functionalized using basic media including NaOCH 3 , KOH, and NaOH, or by forming composites with metal oxides in some cases 145 .…”

“…Based on the results, the use of as‐prepared biochar catalyst for pyrolysis could raise the calorific value along with the pH and greatly lower the viscosity of the pyrolysis oil, thus enhancing its quality. Owing to its large specific surface area, distinctive aromatic structure, numerous electron donor functional groups appearing on the modified biochar catalyst's surface, along with low inorganic salt concentration, reed‐originated biochar provided an excellent precursor for highly active solid acidic catalysts 144 . Meanwhile, Kandasamy et al 161 .…”