Selective Conversion Of Glycerol Research Articles

Metal‐ and Acid‐Free Photocatalytic Approach Using Quinone‐Based Hyper‐Crosslinked Porous Catalysts for the Valorization of Glycerol into Solketal

Two metal‐ and acid‐free anthracene (AN) and anthraquinone (AQ)‐based photocatalysts (HCP‐AQ‐2Ph and HCP‐AN‐2Ph) are synthesized and used for the effective acetalization of glycerol to obtain selectively solketal, an added‐value compound with several industrial applications and high demand as an oxygenated additive of fuels. HCP‐AQ‐2Ph and HCP‐AN‐2Ph are prepared by a Friedel–Crafts coupling reaction between the AQ or AN and biphenyl (2Ph) as comonomer which leads to the formation of high thermally stable hyper‐crosslinked porous networks with specific surface areas of 295 and 596 m2 g−1, respectively. Initial tests suggest that HCP‐AN‐2Ph is a less efficient catalyst compared to HCP‐AQ‐2Ph. However, subsequent runs indicate that during the first trial, the AN units are oxidized, resulting in a catalyst (HCP‐AN(OX)‐2Ph) just as effective as the AQ‐based one. The quantitative and selective conversion of glycerol into solketal is achieved in just 3 h using a 4 wt% catalyst and maintaining this catalytic performance for at least 5 cycles. In addition, the process can be scaled allowing the obtaining of solketal with high purity on a gram scale. These results place these catalysts among the most effective for the selective production of solketal from glycerol compared to previously reported metal‐ or acid‐catalyzed reaction.

Intensified synthesis of glycerol monocaprylin using ionic liquids by temperature-responsive esterification

• [N 1,1,1,1 ][H 2 PO 4 ] is screened by COSMO-RS for selective synthesis of glycerol monocaprylin. • Dual effects of IL as solvent and catalyst are verified by analysis and experiments. • The esterification process with [N 1,1,1,1 ][H 2 PO 4 ] shows a temperature-responsive behavior. • The esterification conditions are optimized to obtain high GMC yield. • The esterification kinetics are correlated with the pseudo-homogeneous model. The selective conversion of glycerol (GL), a surplus by-product in biodiesel production, is deemed as a promising way to produce high value products. Glycerol monocaprylin (GMC), one of the widely utilized industrial chemicals, can be synthesized by esterification of GL with caprylic acid (CA). In this work, the intensified synthesis of GMC is proposed using ionic liquid (IL) as dual solvent and catalyst. The IL namely tetramethylammonium dihydrogen phosphate ([N 1,1,1,1 ][H 2 PO 4 ]) is screened out from 414 acidic IL candidates by calculating the infinite dilution capacity of GL and CA in ILs based on COSMO-RS model. The dual effects of [N 1,1,1,1 ][H 2 PO 4 ] are verified by σ -profile/ σ -potential analysis and experiments. The good solubility of [N 1,1,1,1 ][H 2 PO 4 ] for GL and CA makes the esterification system homogenous during reaction at high temperature, whereas phase splitting occurs after cooling down. Such a temperature-responsive behavior can greatly improve the GMC selectivity and benefit product separation and IL recycling. The reaction conditions are optimized to achieve 87.7% CA conversion and 78.4% GMC yield. The pseudo-homogeneous model is adopted to successfully describe the esterification kinetics with RMSD of 0.0349. Moreover, the recycling tests of [N 1,1,1,1 ][H 2 PO 4 ] are also performed, and the IL can keep its initial catalytic performance after four successive cycles.

Directed glycerol conversion to 2,5-hexanedione and more advanced poly-oxygenates as platform chemicals and high energy–density fuel additives

• Selective conversion of glycerol was achieved by using Cu-catalyst without external supplied H 2 . • Cu-MOF derived catalyst gave a high 2,5-hexanedione yield of 43.4% under mild condition. • MOF-Cu/C catalyst was highly efficient for aldol condensation-hydrogenation reaction. • The selectivity of C10-C12 oxygenates reached up to 70% by increasing reaction time. Bioenergy and biochemicals play a central and critical role to establish energy security and enable the required green and low carbon transition of the gigantic chemical industry amid the great concerns over climate change and sustainable development. Here, we describe the selective catalytic conversion of glycerol to 2,5-hexanedione and other more advanced C6-C12 poly-oxygenates by making use of water hydrogen under relatively mild conditions, using an effective copper metal–organic framework (Cu-MOF) derived catalyst. 2,5-hexanedione is a versatile platform chemical and a key intermediate for producing high energy–density aviation fuels from biomass resources. The catalyst was found to exhibit rarely seen catalytic activities both for the desirable glycerol conversion and for the aqueous reforming reactions for in-situ hydrogen generation, which is essential to drive the conversion to polyoxygenates consisting primarily of polyketones and polyalcohols. The selectivity could reach 43.4% for 2,5-hexanedione formation and over 70% for total C8-C12 poly-oxygenates. Characterizations show that the remarkable catalytic capability of MOF derived catalyst for the formation of novel advanced chemicals arose not only from the highly dispersion of copper in the substrate but also from the unique chemical states of the copper species, which together lead to the formation of greatly enhanced active surface sites with novel catalytic activities that cannot be achieved with similar catalysts prepared with conventional methodologies. Based on the results, the reaction mechanisms responsible for the desirable formation of 2,5-hexanedione were proposed. It is believed that the investigation opens up the possibility of recycling the crude glycerol from biodiesel production to produce novel advanced chemicals and/or high energy density transport fuels or fuel additives.

Selective Conversion of Glycerol into Propylene: Single-Step versus Tandem Process

Dehydration and catalytic cracking reactions can be combined to convert glycerol into light olefins using solid acid catalysts. The combination is suitable for a single-step process to convert glycerol into light olefins at high temperatures (26–36% selectivity at 873 K). However, large quantities of carbon oxides are produced (31–39% COx selectivity), and catalyst deactivation also occurs. High light olefin selectivity (62–65%) and a smaller quantity of carbon oxides (11–12% COx selectivity) can be obtained by using a tandem process involving the dehydration of glycerol and subsequent catalytic cracking of the dehydration products (mainly acetol and acrolein). Furthermore, the ratio of propylene to ethylene can be adjusted by changing the dehydration catalysts to favor the production of acetol or acrolein: Acetol forms propylene, and acrolein forms ethylene. To overcome the fast deactivation of acid catalysts in glycerol dehydration, the hydrogenolysis and catalytic cracking reactions can be synchronized...

Selective Conversion of Glycerol into 1,2-Propanediol at Ambient Hydrogen Pressure

Abstract The vapor-phase reaction of glycerol was performed over a copper–alumina catalyst at ambient hydrogen pressure. Glycerol was converted into 1,2-propanediol (PDO) through dehydration–hydrogenation via hydroxyacetone (HA). We also found that 1,2-PDO was produced at the selectivity higher than 93 mol % in hydrogen flow at gradient temperatures: the dehydrogenation into HA was catalyzed at around 180–200 °C, while the following hydrogenation into 1,2-PDO was catalyzed by Cu–alumina catalyst at around 145–160 °C.

Selective transfer hydrogenolysis of glycerol promoted by palladium catalysts in absence of hydrogen

Selective conversion of glycerol into 1,2-propanediol in the presence of a Pd/Fe2O3catalyst, under inert atmosphere, is reported for the first time; the hydrogen necessary for the hydrogenolysis reaction derives from the dehydrogenation of the solvent (2-propanol or ethanol), promoted by supported palladium, itself reduced “in situ” by alcohols.