Catalytic Production of Oxygenated and Hydrocarbon Chemicals From Cellulose Hydrogenolysis in Aqueous Phase

Abstract

As the most abundant polysaccharide in lignocellulosic biomass, a clean and renewable carbon resource, cellulose shows huge capacity and roused much attention on the methodologies of its conversion to downstream products, mainly including platform chemicals and fuel additives. Without appropriate treatments in the processes of cellulose decompose, there are some by-products that may not be chemically valuable or even truly harmful. Therefore, higher selectivity and more economical and greener processes would be favored and serve as criteria in a correlational study. Aqueous phase, an economically accessible and immensely potential reaction system, has been widely studied in the preparation of downstream products of cellulose. Accordingly, this mini-review aims at making a related summary about several conversion pathways of cellulose to target products in aqueous phase. Mainly, there are four categories about the conversion of cellulose to downstream products in the following: (i) cellulose hydrolysis hydrogenation to saccharides and sugar alcohols, like glucose, sorbitol, mannose, etc.; (ii) selective hydrogenolysis leads to the cleavage of the corresponding glucose CC and CO bond, like ethylene glycol (EG), 1,2-propylene glycol (PG), etc.; (iii) dehydration of fructose and further oxidation, like 5-hydroxymethylfurfural (HMF), 2,5-furandicarboxylic acid (FDCA), etc.; and (iv) production of liquid alkanes via hydrogenolysis and hydrodeoxygenation, like pentane, hexane, etc. The representative products were enumerated, and the mechanism and pathway of mentioned reaction are also summarized in a brief description. Ultimately, the remaining challenges and possible further research objects are proposed in perspective to provide researchers with a lucid research direction.

Commodity Chemicals and Fuels from Biomass: Thermodynamic Properties of Levoglucosan Derivatives

“…Levoglucosenone can be hydrogenated to Cyrene (dihydrolevoglucosenone) according to the reaction given in Figure …”

“…There are many ways to use levoglucosan to produce commodity chemicals. 58 For example, the production of levoglucosenone via Brønsted solid acid-catalyzed dehydration of levoglucosan in tetrahydrofuran (THF) was reported just recently 59 and is shown in Figure 7.…”

“…Levoglucosenone can be hydrogenated to Cyrene (dihydrolevoglucosenone) according to the reaction given in Figure 8. 58 The reaction enthalpy, Δ r H m o (liq, 298.15 K) = −114.4 ± 2.3 kJ•mol −1 , which was calculated from our new data (see Table 11) for both reaction participants, is in agreement with the enthalpy of hydrogenation of cyclohexene to cyclohexane, Δ r H m o (liq, 298.15 K) = −117.9 ± 1.0 kJ•mol −1 , calculated with literature data. 57 The relatively high exothermic effect of the hydrogenation reaction must be taken into account when developing the technology for temperature management.…”

Recent advances in the valorization of plant biomass

“…Lignocellulose biomass is very rich in pentose and hexose sugars. After pretreatment and enzymatic hydrolysis, monosaccharides, sugar-related alcohols and acids are obtained, such as glucose, xylose, arabinose, sorbitol, mannitol, glucuronic acid, and galacturonic acid [ 103 ]. Among these compounds, sorbitol, mannitol, glucose, and xylose then become the primary carbon sources for the next step.…”

Valorisation of plastic waste via metal-catalysed depolymerisation

“…The excess of H 2 reagent can also be easily removed from the reaction mixture. The approach, referred to as hydrodeoxygenation [ 95 – 96 ], is already in use for the valorisation of naturally-occurring polymeric waste, i.e., lignocellulosic biomass [ 97 – 98 ], particularly lignin [ 99 – 100 ] and cellulose [ 101 ], to monomers or added-value platform molecules [ 102 – 103 ]. Here the main drawbacks concern safety hazards, supply, transport and storage costs of hydrogen.…”