Existing technologies to produce liquid fuels from biomass are typically energy-intensive, multistep processes. Many of these processes use edible biomass as starting material. Carbohydrates, such as mono- and polysaccharides and cellulose, typically constitute 50-80% of plant biomass. Herein, we report that hexose from a wide range of biomass-derived carbohydrates, cellulose, and even raw lignocellulose (e.g., corn stover) can be converted into 2,5-dimethyltetrahydrofuran (DMTHF) in one step, in good yields and under mild conditions in water. Under the same conditions, 2-methyltetrahydrofuran is formed from pentose. The reaction employs a soluble rhodium catalyst, dihydrogen, and HI/HCl+NaI. The catalytic system is robust and can be recycled repeatedly without loss of activity. DMTHF is superior to ethanol and has many of the desirable properties currently found in typical petroleum-derived transportation fuels.
Integrating nitrogen species into sp 2-hybridized carbon materials has proved an efficient means to improve their electrochemical performance. Nevertheless, an inevitable mixture of nitrogen species in carbon materials, due to the uncontrolled conversion among different nitrogen configurations involved in synthesizing nitrogen-doped carbon materials, largely retards the precise identification of electrochemically active nitrogen configurations for specific reactions. Here, we report the preparation of single pyrrolic N-doped carbon materials (SPNCMs) with a tunable nitrogen content from 0 to 4.22 at.% based on a strategy of low-temperature dehalogenation-induced and subsequent alkaline-activated pyrolysis of 3-halogenated phenol-3-aminophenol-formaldehyde (X-APF) co-condensed resins. Additionally, considering that the pseudocapacitance of SPNCMs is positively dependent on the pyrrolic nitrogen content, it could be inferred that pyrrolic nitrogen species are highly active pseudocapacitive sites for nitrogen-doped carbon materials. This work gives an ideal model for understanding the contribution of pyrrolic nitrogen species in N-doped carbon materials.
5‐Methylfurfural (MF), an important chemical intermediate, can be obtained directly from carbohydrates using a metal catalyst, hydroiodic acid, and hydrogen in a biphasic reaction procedure. The catalyst system is robust and can be recycled without loss of reactivity.
Carbohydrates, such as fructose, can be fully dehydroxylated to 2,5-dimethyltetrahydrofuran (DMTHF), a valuable chemical and potential gasoline substitute, by the use of a dual catalytic system consisting of HI and RhX(3) (X=Cl, I). A mechanistic study has been carried out to understand the roles that both acid and metal play in the reaction. HI serves a two-fold purpose: HI acts as a dehydration agent (loss of 3 H(2)O) in the initial step of the reaction, and as a reducing agent for the conjugated carbinol group in a subsequent step. I(2) is formed in the reduction step and metal-catalyzed hydrogenation reforms HI. The rhodium catalyst, in addition to catalyzing the reaction of iodine with hydrogen, functions as a hydrogenation catalyst for C=O and C=C bonds. A general mechanistic scheme for the overall reaction is proposed based on identification of intermediates, independent reactions of the intermediates, and deuterium labeling studies.
Currently, low intimacy between hydrogenation sites and acidic sites causes unsatisfactory catalytic activity and selectivity for the synthesis of 2,5-hexanedione from C 6 furan aldehydes (5methylfurfural, 5-hydroxymethylfurfural). Herein, iodine(I) modification of Pd-supported catalysts (such as PdI/Al 2 O 3 and PdI/ SiO 2 ) was investigated to modulate the hydrogenation sites and acidic sites. Unlike Pd catalysts that produced 71.4 % yield of 2hydroxymethyl-5-methyl tetrahydrofuran via an overhydrogenation route of 5-methylfurfural, PdI catalysts showed a high efficiency for 2,5-hexanedione with 93.7 % yield by a hydro-genative ring-opening route. More importantly, the selective synthesis of 2,5-hexanedione from 5-hydroxymethylfurfural with a high yield of 50.2 % by the hydrogenolysis and subsequent ring-opening route was reported for the first time. I-modified Pd nanoparticles produced in-situ hydrogen spillover, which promoted the selective C=O hydrogenation and ring-opening steps by regulating the adsorption configuration of the reactants and the transformation of Lewis to Brønsted acidity, respectively.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.