Improving the Fractionated Catalytic Oxidation of Lignocellulosic Biomass to Formic Acid and Cellulose by Using Design of Experiments

Abstract

The main objective of this contribution was to optimize the process conditions for a fractionated oxidation of lignocellulosic biomass (e.g., wood) to produce formic acid and cellulose for further applications. Using the Lindqvist-type polyoxometalate K 5 V 3 W 3 O 19 as a homogeneous catalyst in aqueous media, we were able to selectively oxidize the hemicellulose and lignin fractions. While hemicellulose and lignin are converted to formic acid, the cellulose fraction remains untapped. Furthermore, we optimized the process conditions with the help of a Box−Behnken design of experiments. Thereby improved conditions showed an output of formic acid from lignin three times higher compared with the initial parameters. Furthermore, recycling of the catalyst has been carried out successfully without observing significant changes in vanadium species. Finally, we investigated the conversion of different real biomasses (hardwood, softwood, and algae) leading to new structure−performance relationships.

Keggin‐type Heteropolyacids‐Catalyzed Selective Hydrothermal Oxidation of Microalgae for Low Nitrogen Biofuel Production

“…The HPA-4 is advantageous to the depolymerization and hydrolysis of lipids to form carboxylic acids, such as oleic acid, and octadecanoic acid, leading to a continuous increase of biocrude yield with the increase of reaction time, initially. [42,43] However, these carboxylic acids are hydrolyzed and oxidized into smaller carboxylic acids molecules, water soluble organics, and gaseous products with increase of reaction time, correspondingly resulting in a dramatical decrease of biocrude yield. [44] Furthermore, the repolymerization or condensation of chemical intermediates, beneficial to residue production, are the dominate thermochemical reactions of intermediates once the depolymerization and hydrolysis are finished, attributing to the decrease of biocrude yield when the reaction time is longer than 2 h.…”

“…The HPAs are reduced during the oxidation of reducing monosaccharide, while they are oxidized via oxygen for their continuous catalyzation of HTL of microalgae as presented in Equations (2) and (3). [42,45] Cellulose þHPAsðoxÞ ! Organic Acids þ HPAsðredÞ…”

Catalytic Upgrading of Bio‐Based 5‐Hydroxymethylfurfural to 2,5‐Dimethylfuran with Non‐Noble Metals

“…[38] Formic acid is considered to be a low-cost ideal hydrogen donor due to its high energy density, good stability, safety, and renewability, and it is mainly obtained from cellulosic biomass or reduction of CO 2 . [39][40][41][42] Using formic acid as a hydrogen donor, HMF could be selectively hydrogenated to DMF using a CoFe bimetallic catalyst. The reaction was conducted at 240 C for 2 h to obtain a DMF yield of more than 92%.…”

Oxidative Transformation of Biomass into Formic Acid

“…Later, in 2019, group of Albert used Lindqvist‐type polyoxometalate (K 5 V 3 W 3 O 19 ) as a homogeneous catalyst in aqueous media for the selective oxidation of hemicellulose and lignin moiety for the formation of FA and cellulose [32] . Notably, upon application of their system on real biomass like beech (hard wood), spruce (soft wood) showed satisfactory results for the selective formation of FA.…”