Waste Biomass Selective and Sustainable Photooxidation to High-Added-Value Products: A Review

Abstract

Researchers worldwide seek to develop convenient, green, and ecological production processes to synthesize chemical products with high added value. In this sense, lignocellulosic biomass photocatalysis is an excellent process for obtaining various outcomes for the industry. One issue of biomass transformation via heterogeneous catalysis into valuable chemicals is the selection of an adequate catalyst that ensures high conversion and selectivity at low costs. Titanium oxide (TiO2), is widely used for several applications, including photocatalytic biomass degradation, depolymerization, and transformation. Graphite carbon nitride (g-C3N4) is a metal-free polymeric semiconductor with high oxidation and temperature resistance and there is a recent interest in developing this catalyst. Both catalysts are amenable to industrial production, relatively easy to dope, and suited for solar light absorption. Recent investigations also show the advantages of using heterojunctions, for biomass derivates production, due to their better solar spectrum absorption properties and, thus, higher efficiency, conversion, and selectivity over a broader spectrum. This work summarizes recent studies that maximize selectivity and conversion of biomass using photocatalysts based on TiO2 and g-C3N4 as supports, as well as the advantages of using metals, heterojunctions, and macromolecules in converting cellulose and lignin. The results presented show that heterogeneous photocatalysis is an interesting technology for obtaining several chemicals of industrial use, especially when using TiO2 and g-C3N4 doped with metals, heterojunctions, and macromolecules because these modified catalysts permit higher conversion and selectivity, milder reaction conditions, and reduced cost due to solar light utilization. In order to apply these technologies, it is essential to adopt government policies that promote the use of photocatalysts in the industry, in addition to encouraging active collaboration between photooxidation research groups and companies that process lignocellulosic biomass.

Fe-Loaded Montmorillonite/TiO2 Composite as a Promising Photocatalyst for Selective Conversion of Glucose to Formic Acid under Visible-Light Irradiation

“…In the 10: 90 (W: ACN vol%), glucose conversion and formic acid formation reached 83% and 44%, respectively, compared to 13% glucose conversion and 4% formic acid production in pure water. The better formic acid selectivity after increasing the ACN content in the solvent could be attributed to the low water content, leading to a lower concentration of highly unselective • OH radicals, which is similar to the previous works [5,26,37].…”

Lignocellulosic Biomass in Nanopesticides: A Path toward Sustainable Agriculture

“…13,14 Among various biomass resources are wood, agricultural residues, forestry residues, food waste, algae, vegetable oils, and others. 11,15 It is essential to emphasize the significance of lignin, a key component of lignocellulose, in the efficient harnessing of this valuable renewable-energy source.…”

“…Biomass is often considered waste; however, labeling lignocellulosic material as “waste” is deemed inappropriate due to its potential application . Biomass plays a crucial role as a renewable-energy source in the production of high-efficiency chemicals and fuels. , Among various biomass resources are wood, agricultural residues, forestry residues, food waste, algae, vegetable oils, and others. , It is essential to emphasize the significance of lignin, a key component of lignocellulose, in the efficient harnessing of this valuable renewable-energy source.…”

New Insights into N-Doped Porous Carbons as Both Heterogeneous Catalysts and Catalyst Supports: Opportunities for the Catalytic Synthesis of Valuable Compounds

“…The incorporation of nitrogen during carbonization can be achieved by introducing nitrogen-rich compounds or waste materials that already contain nitrogen functionalities. Waste-derived N -doped carbons have the potential for not only reduced waste disposal but also to produce valuable carbon materials that can be used in various applications, while also addressing waste management challenges [ 38 ].…”