This thesis examines the catalytic characteristics of two materials with respect to the decomposition of Formic Acid. The decomposition of formic acid proceeds via two principal reaction pathways: dehydration and dehydrogenation. Dehydrogenation is a valuable reaction producing Hydrogen suitable for use in fuel cells whereas the dehydration pathway produces carbon monoxide, a poison for many fuel cell materials. One of the surface species, the formate ion, is also implicated in other important chemical reactions, most notably the water gas shift and the decomposition of methanol. The author seeks to document various intermediate surface species associated with the two reaction pathways with hope to use this information to future tailoring of catalysts for greater selectivity.

Though petroleum fuels are currently a crucial part of our daily life, there is interest in developing energy sources that are more sustainable and better for the environment. One possible energy source is hydrogen, which burns cleanly to produce only water as a byproduct. However, hydrogen itself cannot be easily transported and, therefore, other storage mediums are necessary. One such storage medium that has been investigated in recent years is formic acid, which is a liquid at room temperature and easier to handle. A crucial aspect of using formic acid is the ability to release hydrogen on demand. Testing possible catalysts for this transformation has driven my research over the last five years. Chapter 1 investigates the ability of a series of cyclopentadienyl molybdenum hydrides, Cp^RMo(PMe₃)_{3-x}(CO)_xH (Cp^R = C₅H₅, C₅Me₅; x = 0, 1, 2, 3), to catalyze formic acid dehydrogenation. Though several compounds in the series CpRMo(PMe₃)_{3-x}(CO)_xH have been structurally characterized before, we were able to characterize several more by X-ray diffraction. Since the compounds are structurally similar, differences in catalytic activity are governed by the electronics, which are determined primarily by the number of PMe₃ ligands relative to CO. The best catalysts are the hybrid compounds, Cp^RMo(PMe₃)₂(CO)H, due to the fact that they can be easily protonated by formic acid and readily release hydrogen to continue the catalytic cycle. Additionally, I observed that methanol and methyl formate were being produced as side products. Since methanol is also a potential hydrogen storage medium, its production is of interest. In this case, the tricarbonyl compounds, Cp^RMo(CO)₃H, were most selective for formic acid disproportionation relative to dehydrogenation. This is likely due to their relative propensity to transfer a hydride ligand to formic acid rather than to become protonated by it. We also investigated the ability of formic acid to reduce ketones and aldehydes via transfer hydrogenation. Because the phosphine-rich compounds were such effective catalysts, we sought to investigate the reactivity of other compounds with phosphine ligands towards formic acid. To this end, Chapter 2 focuses on studies involving Ni(PMe₃)₄, and Chapter 3 looks at Mo(PMe₃)₆ and W(PMe₃)₄(η²-CH₂PMe₂)H. Ni(PMe₃)₄ is indeed able to catalyze formic acid dehydrogenation. Density Functional Theory studies suggest that the mechanism involves formation of a formate-hydride followed by decarboxylation to produce a dihydride species. The ability of the PMe₃ ligand to induce decarboxylation also provides a route to synthesize Ni(PMe₃)₄ from Ni(O₂CH)₂•2H₂O and Ni(py)₄(O₂CH)₂•2py, which has been structurally characterized. To expand on the nickel phosphine reactivity, a heteroleptic nickel phosphine complex employing the bisphosphine ligand 1,2-bis(diphenylphosphino)benzene (bppb), namely (bppb)Ni(PMe₃)₂, was synthesized, characterized and tested with formic acid. It also catalyzes dehydrogenation, but rearranges to Ni(PMe₃)₄ and the inactive compound, (bppb)₂Ni. The structural characterization of these and other (bppb)Ni compounds shows that the bppb ligand allowed for extreme flexibility in crystallization. Chapter 3 reveals that Mo(PMe₃)₆ and W(PMe₃)₄(η²-CH₂PMe₂)H are likewise catalysts for formic acid dehydrogenation. However, the compounds produced along the way are also of interest. The known carbonate species, Mo(PMe₃)₄H₂(O₂CO), is formed from Mo(PMe₃)₆ and formic acid, and we have structurally characterized it. The tungsten carbonate species is also produced in the analogous reaction with W(PMe₃)₄(η²-CH₂PMe₂)H. Other compounds observed include W(PMe₃)₄H₂(O₂CH)₂ and W(PMe₃)₄H₃(O₂CH), the latter of which has also been characterized by X-ray diffraction. Finally, both Mo(PMe₃)₆ and W(PMe₃)₄(η²-CH₂PMe₂)H react with formic acid to make trimeric species, [M(PMe₃)₃(CO)(O₂CH)(μ-O₂CH)]₃ (M = Mo, W), which display an unusual anti/anti configuration of the bridging formate ligands. Chapter 4 revisits some of the side products from Chapter 1 in more detail, particularly [CpMo(CO)₃]₂ and [CpMo(μ-O)(μ-O₂CH)]₂. The presence of semi-bridging and bridging ligands, respectively, makes it difficult to determine whether there is actually a metal-metal bond. Natural Bond Orbital (NBO) analysis reveals that there is indeed a Mo-Mo bond in [CpMo(CO)₃]₂, but not in [CpMo(μ-O)(μ-O₂CH)]₂. The Covalent Bond Classification method can be used to depict these and other compounds in a way that more accurately reflects the true bonding in the molecule.

This thesis examines the catalytic characteristics of two materials with respect to the decomposition of Formic Acid. The decomposition of formic acid proceeds via two principal reaction pathways: dehydration and dehydrogenation. Dehydrogenation is a valuable reaction producing Hydrogen suitable for use in fuel cells whereas the dehydration pathway produces carbon monoxide, a poison for many fuel cell materials. One of the surface species, the formate ion, is also implicated in other important chemical reactions, most notably the water gas shift and the decomposition of methanol. The author seeks to document various intermediate surface species associated with the two reaction pathways with hope to use this information to future tailoring of catalysts for greater selectivity.

Based on Thesis (PH. D.)--University of Michigan, 1944. / Cover title. "Contribution from the Chemical laboratory of the University of Michigan." "Reprinted from the Journal of the American chemical society, 66 ... (1944)." Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 32-33.

This thesis examines the catalytic characteristics of two materials with respect to the decomposition of Formic Acid. The decomposition of formic acid proceeds via two principal reaction pathways: dehydration and dehydrogenation. Dehydrogenation is a valuable reaction producing Hydrogen suitable for use in fuel cells whereas the dehydration pathway produces carbon monoxide, a poison for many fuel cell materials. One of the surface species, the formate ion, is also implicated in other important chemical reactions, most notably the water gas shift and the decomposition of methanol. The author seeks to document various intermediate surface species associated with the two reaction pathways with hope to use this information to future tailoring of catalysts for greater selectivity.

Alternative energy sources have been investigated for utilization in various applications to mitigate carbon dioxide emissions. The transportation sector is one of the major sectors that require the adaptation of renewable energy storage technologies for onboard applications. Formic acid is a liquid energy carrier that has the potential of replacing current fuels and mitigating carbon dioxide emissions through a circular carbon economy. The production of energy from formic acid can be achieved by homogenous catalysis to extract hydrogen from formic acid. The most promising metals for formic acid dehydrogenation in aqueous solution have been mainly ruthenium and iridium. While iridium has mostly surpassed ruthenium, further exploration of ruthenium is necessary because it is more economical. This work presents the synthesis and catalytic performance of a N,N-bidentate Ru(II) complex. X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and Mass spectrometry (MS) were used to confirm the structure of the catalyst. The title complex was found to be an efficient system for formic acid dehydrogenation to hydrogen gas and carbon dioxide in the aqueous phase. The highest TOF achieved is 656 h-1 in the presence of two equivalents of sodium formate to formic acid in water at 90 °C. There was no detection of carbon monoxide throughout the reaction process, suggesting the high selectivity of this catalytic system.

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The chemical industry of today is under increased pressure to develop novel green materials, bio-fuels as well as sustainable chemicals for the chemical industry. Indeed, the endeavour is to move towards more eco-friendly cost efficient production processes and technologies and chemical transformation of renewables has a central role considering the future sustainable supply of chemicals and energy needed for societies. In the Nordic countries, the importance of pulping and paper industry has been particularly pronounced and the declining European demand on these products as a result of our digitalizing world has forced the industry to look at alternative sources of revenue and profitability. In this thesis, the production of levulinic and formic acid from biomass and macromolecules has been studied. Further, the optimum reaction conditions as well as the influence of the catalyst and biomass type were also discussed. Nordic sulphite and sulphate (Kraft) cellulose originating from two Nordic pulp mills were used as raw materials in the catalytic synthesis of green platform chemicals, levulinic and formic acids, respectively. The catalyst of choice used in this study was a macro-porous, cationic ion-exchange resin, Amberlyst 70, for which the optimal reaction conditions leading to best yields were determined. Cellulose from Nordic pulp mills were used as raw materials in the catalytic one-pot synthesis of ‘green’ levulinic and formic acid. The kinetic experiments were performed in a temperature range of 150–200 °C and an initial substrate concentration regime ranging from 0.7 to 6.0 wt %. It was concluded that the most important parameters in the one-pot hydrolysis of biomass were the reaction temperature, initial reactant concentration, acid type as well as the raw material applied. The reaction route includes dehydration of glucose to hydroxymethylfurfural as well as its further rehydration to formic and levulinic acids. The theoretical maximum yield can hardly be obtained due to formation of humins. For this system, maximum yields of 59 mol % and 68 mol % were obtained for formic and levulinic acid, respectively. The maximum yields were separately obtained in a straight-forward conversion system only containing cellulose, water and the heterogeneous catalyst. These yields were achieved at a reaction temperature of 180 °C and an initial cellulose intake of 0.7 wt % and belong to the upper range for solid catalysts so far presented in the literature. The reaction network of the various chemical species involved was investigated and a simple mechanistic approach involving first order reaction kinetics was developed. The concept introduces a one-pot procedure providing a feasible route to green platform chemicals obtained via conversion of coniferous soft wood pulp to levulinic and formic acids, respectively. The model was able to describe the behaviour of the system in a satisfactory manner (degree of explanation 97.8 %). Since the solid catalyst proved to exhibit good mechanical strength under the experimental conditions applied here and a one-pot procedure providing a route to green platform chemicals was developed. A simplified reaction network of the various chemical species involved was investigated and a mechanistic approach involving first order reaction kinetics was developed.