Critical Review on the Preparation of Platform Compounds from Biomass or Saccharides via Hydrothermal Conversion over Carbon-Based Solid Acid Catalysts

Abstract

The use of carbon-based catalysts to catalyze the hydrothermal conversion of biomass and its derived carbohydrates to produce platform compounds such as 5-(hydroxymethyl)­furfural (HMF), levulinic acid (LA), and furfural (FF) has a long history. The excellent thermal stability and chemical activity and low preparation cost of carbon-based catalysts make them develop rapidly in catalytic hydrothermal conversion, which is the core attention in the review. Carbon catalysts are divided into sulfuric acid-based carbon catalysts, phosphoric acid-based carbon catalysts, metal-supported carbon catalysts and other types of carbon catalysts, to study their application to hydrothermal decomposition of monosaccharides, disaccharides, polysaccharides, and biomass. The characteristics of different types of carbon catalysts were introduced. The diversified development of carbon-based catalysts and the upgrading of feedstocks have promoted the improvement of product selectivity, cost, and energy optimization, realizing the transformation of hydrothermal decomposition of biomass into a greener process. However, the development of efficient catalytic systems for hydrothermal conversion of abundant, cheap, and readily available biomass sources is still an ideal choice to expand the process strategy.

Microwave-Assisted Efficient Fructose–HMF Conversion in Water over Sulfonated Carbon Microsphere Catalyst

“…22−24 Particularly, carbon-based nanomaterials have attracted much attention in the development of sustainable catalysts for green chemistry. 25 The different morphologies of carbon materials make it more attractive in catalysis, energy, and environmental applications. In addition, carbon-based solid acid catalysts have more advantages than other heterogeneous catalysts, such as easy preparation by carbonization from available cheap biomass resources, easily functionalized, can be tuned to have a more porous structure, low density, and easily recyclable.…”

“…26 In recent years, sulfonated carbons and other heterogeneous solid acid catalysts have been reported for HMF synthesis from carbohydrate derivatives. 25 For example, biomass resources have been used to prepare carbon materials by hydrothermal, pyrolysis, or mechanochemical carbonization methods followed by sulfonation in one or two steps for HMF production. 27,28 Apart from carbon materials, bifunctionalized carbonaceous sulfonic group grafted halloysite nanotubes, sulfonated ordered mesoporous carbons or organosilica, sulfonated metal oxides, and sulfonated metal−organic frameworks have been reported for HMF production with excellent yields.…”

“…A number of studies have reported the effects of various solid acid catalysts on carbohydrate–HMF conversion. − Particularly, carbon-based nanomaterials have attracted much attention in the development of sustainable catalysts for green chemistry . The different morphologies of carbon materials make it more attractive in catalysis, energy, and environmental applications.…”

“…In addition, carbon-based solid acid catalysts have more advantages than other heterogeneous catalysts, such as easy preparation by carbonization from available cheap biomass resources, easily functionalized, can be tuned to have a more porous structure, low density, and easily recyclable . In recent years, sulfonated carbons and other heterogeneous solid acid catalysts have been reported for HMF synthesis from carbohydrate derivatives . For example, biomass resources have been used to prepare carbon materials by hydrothermal, pyrolysis, or mechanochemical carbonization methods followed by sulfonation in one or two steps for HMF production. , Apart from carbon materials, bifunctionalized carbonaceous sulfonic group grafted halloysite nanotubes, sulfonated ordered mesoporous carbons or organosilica, sulfonated metal oxides, and sulfonated metal–organic frameworks have been reported for HMF production with excellent yields. − Besides, sulfonated solid acid carbon-based catalysts have significant activity in carbohydrate-to-HMF production. − However, most HMF formation reactions from carbohydrates were generally performed via conventional heating and commonly required severe reaction conditions such as organic solvents and longer reaction times.…”

Facile self-propagated carbonization synthesis of phosphorus-doped carbon-based catalysts for partial oxidation and hydrogenation

“…15 Among them, carbonization of a carbon-containing precursor mixed/combined with a phosphorus-containing compound is commonly used, in which phosphoric acid is widely reported to activate different biomass carbon precursors including glucose, 16,17 sucrose, 18,19 cellulose or lignin 20,21 to prepare phosphorus-containing functional groups on the carbon material. 22,23 However, such methods for preparing phosphorus-doped carbon materials usually require tedious preparation steps and high-temperature calcination. Therefore, it is highly desirable to develop a simple and efficient preparation method for phosphorus-doped carbon materials.…”