Hydrogen from Formic Acid via Its Selective Disproportionation over Nanodomain-Modified Zeolites

Abstract

Sodium germanate is a nontransition-metal catalyst that is active in the selective dehydrogenation of formic acid. However, bulk sodium germanate has a very low surface area, limiting the availability of the germanate sites for catalysis. The dispersion of germanate in the zeolite ZSM-5 has been investigated both computationally and experimentally as a method for the provision of greater surface area and, therefore, higher activity per germanate site. Nanodomain islets of germanate dispersed in the germanium ZSM-5 zeolite invert selectivity from dehydration (in ZSM-5) to dehydrogenation of formic acid, potentially making Na-Ge-ZSM-5 a cost-effective catalyst for releasing hydrogen from formic acid.

Theory‐Based Extension of the Catalyst Scope in the Base‐Catalyzed Hydrogenation of Ketones: RCOOH‐Catalyzed Hydrogenation of Carbonyl Compounds with H2 Involving a Proton Shuttle

“…In cases considered herein, H 2 binding is slightly exothermic at the level of just a few kcal mol −1 . This is in agreement with the data reported in the literature describing, for example, the reactant complexes pertaining to the FLP cleavage of H 2 as well as other non‐metal‐catalyzed hydrogenation reactions using H 2 . It is known that adequately accurate calculation of the Gibbs free‐energy difference describing an interaction of solvated H 2 with solvated metal‐free reactants can be an arduously challenging task and is far beyond the scope of this article (also typically the case for other computational articles describing mechanisms of the metal‐free hydrogenation reactions with H 2 ).…”

“…We will look into this a bit deeper at the end of the main section of this article, but right now we would like to point out that such an element, that is, the hydrogen bond, is not farfetched. Such an interaction is found for a family of zeolite‐catalyzed hydrogenation reactions of carbon dioxide (O=C=O) in which OH⋅⋅⋅O=C hydrogen bonding plays critical role . In addition, asymmetric catalysis by chiral hydrogen‐bond donors and the metal‐free organocatalysis involving hydrogen‐bonding interactions have been observed.…”

“…It is worth noting that the critical role of the O−H⋅⋅⋅O=C bonding motif has been pointed out by experimental investigations on how the resonance‐assisted hydrogen bonding in β‐diketone enols affects the configuration . Also a relevant analogy is the mechanism of the zeolite‐catalyzed hydrogenation of carbon dioxide according to the report by Chan and Radom, for example, Scheme 4 in reference , in which there is 1) hydrogen bonding of O=C=O to the OH group of a model zeolite, and 2) the TS structure includes proton transfer from the OH group of a model zeolite in concert with the heterolytic cleavage of H 2 , in which carbon of O=C=O accepts the hydride as the LA center and a “spare” oxygen of a model zeolite accepts the proton as the LB center. In short, the HO−X−O fragment of a model zeolite with X denoting a Group 3 element of the periodic table (e.g., Al or Ga) according to the report by Chan and Radom in reference is more or less exactly what we now propose for the bifunctional role of carboxylic acid in Scheme .…”

Formic Acid or Formate Derivatives as the In Situ Hydrogen Source in Au‐Catalyzed Reduction of para‐Chloronitrobenzene

“…It had been reported that Au catalyst show superior activity on the decomposition of HCOOH. Furthermore, Au catalyst owning high selectivity hydrogenation of para‐ chloronitrobenzene, compared to other precious metal, have attracted much attention . Thus, it is of interest to examine the catalytic hydrogenation of para‐ chloronitrobenzene over Au catalyst with HCOOH or formate derivatives as the reducing agent precursor.…”

Applications of Zeolites to C1 Chemistry: Recent Advances, Challenges, and Opportunities

“…Pure zeolites with Brønsted acidities have been demonstrated to be active in gas‐phase HCOOH decomposition reactions, including dehydrogenation and dehydration. [ 147 ] Both computational and experimental results indicate that the HZSM‐5 zeolite favors dehydration over dehydrogenation of HCOOH molecules, leading to a low hydrogen selectivity of 21%. According to computational investigations, the barriers of dehydrogenation and dehydration of HCOOH in HZSM‐5 zeolites are 199.0 kJ mol −1 and 158.6 kJ mol −1 , respectively.…”