Efficient methodologies for converting biomass solids to liquid fuels have the potential to reduce dependence on imported petroleum while easing the atmospheric carbon dioxide burden. Here, we report quantitative catalytic conversions of wood and cellulosic solids to liquid and gaseous products in a single stage reactor operating at 300-320 °C and 160-220 bar. Little or no char is formed during this process. The reaction medium is supercritical methanol (sc-MeOH) and the catalyst, a copper-doped porous metal oxide, is composed of earth-abundant materials. The major liquid product is a mixture of C(2)-C(6) aliphatic alcohols and methylated derivatives thereof that are, in principle, suitable for applications as liquid fuels.

Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

A (super)critical transfer: The consecutive hydrogenolysis and hydrogenation of the lignin model compound dihydrobenzofuran was studied in supercritical methanolic solutions using porous metal oxide catalysts. These catalysts promote H(2) production from methanol followed by hydrogenolysis of the ether linkages and reduction of the aromatic rings, leading principally to a mixture of cyclohexanols.

The water-soluble ferriheme model Fe(III)(TPPS) mediates oxygen atom transfer from inorganic nitrite to a water-soluble phosphine (tppts), dimethyl sulfide, and the biological thiols cysteine (CysSH) and glutathione (GSH). The products with the latter reductant are the respective sulfenic acids CysS(O)H and GS(O)H, although these reactive intermediates are rapidly trapped by reaction with excess thiol. The nitrosyl complex Fe(II)(TPPS)(NO) is the dominant iron species while excess substrate is present. However, in slightly acidic media (pH ≈ 6), the system does not terminate at this very stable ferrous nitrosyl. Instead, it displays a matrix of redox transformations linking spontaneous regeneration of Fe(III)(TPPS) to the formation of both N2O and NO. Electrochemical sensor and trapping experiments demonstrate that HNO (nitroxyl) is formed, at least when tppts is the reductant. HNO is the likely predecessor of the N2O. A key pathway to NO formation is nitrite reduction by Fe(II)(TPPS), and the kinetics of this iron-mediated transformation are described. Given that inorganic nitrite has protective roles during ischemia/reperfusion (I/R) injury to organs, attributed in part to NO formation, and that HNO may also reduce net damage from I/R, the present studies are relevant to potential mechanisms of such nitrite protection.

Described are new solid base catalysts for transesterification of seed oil triglycerides to fatty acid methyl esters, a key step in biodiesel production. These were prepared by substituting Fe3+ ions substitute for a fraction of the Al3+ ions in the Mg/Al layered double hydroxide lattices of hydrotalcites (HTC) and calcining to give porous metal oxides (PMOs). These iron-doped PMOs are much stronger bases than those derived from undoped or Ga3+ doped HTCs and are effective catalysts for the methanol transesterification of triacetin (glycerol triacetate) and of soybean oil.

Kinetics studies provide mechanistic insight regarding the formation of dinitrosyl iron complexes (DNICs) now viewed as playing important roles in the mammalian chemical biology of the ubiquitous bioregulator nitric oxide (NO). Reactions in deaerated aqueous solutions containing FeSO 4 , cysteine (CysSH), and NO demonstrate that both the rates and the outcomes are markedly pH dependent. The dinuclear DNIC Fe 2 (μ-CysS) 2 (NO) 4 , a Roussin's red salt ester (Cys-RSE), is formed at pH 5.0 as well as at lower concentrations of cysteine in neutral pH solutions. The mononuclear DNIC Fe(NO) 2 (CysS) 2 − (Cys-DNIC) is produced from the same three components at pH 10.0 and at higher cysteine concentrations at neutral pH. The kinetics studies suggest that both Cys-RSE and Cys-DNIC are formed via a common intermediate Fe(NO)(CysS) 2 − . Cys-DNIC and Cys-RSE interconvert, and the rates of this process depend on the cysteine concentration and on the pH. Flash photolysis of the Cys-RSE formed from Fe(II)/NO/cysteine mixtures in anaerobic pH 5.0 solution led to reversible NO dissociation and a rapid, second-order back reaction with a rate constant k NO = 6.9 × 10 7 M −1 s −1 . In contrast, photolysis of the mononuclear-DNIC species Cys-DNIC formed from Fe(II)/ NO/cysteine mixtures in anaerobic pH 10.0 solution did not labilize NO but instead apparently led to release of the CysS • radical. These studies illustrate the complicated reaction dynamics interconnecting the DNIC species and offer a mechanistic model for the key steps leading to these non-heme iron nitrosyl complexes.

Forty percent of all carbon dioxide emissions are attributed to burning fossil fuels (coal, natural gas, oil) for power generation. 1,2 CO 2 emissions from such sources are expected to double current emissions owing to the construction of new coal-fired power plants, ∼100 per year for the next 25 years. 3 The global carbon cycle currently is unbalanced by 3.2 gigatons of excess CO 2 ; 4 therefore, it is essential to capture most carbon dioxide emitting from such current and future stationary sources. Unfortunately, known CO 2 sorbents for these applications suffer either from early depletion or from large energy requirements for regeneration 2 and, if installed, would also bring an 8-35% energy penalty. [5][6][7] Moreover, CO 2 from hot gas streams, such as exhaust from fossil fuel based power plants, 8,9 requires robust materials that either operate or are stable at elevated temperatures. 10,11 Hydrotalcites (HTs) belong to a family of layered, double hydroxide solids that have been proven to be stable adsorbents under harsh conditions. 12 The stoichiometry 13,14 of these solids is M 2þ1 -x M 3þx ðOHÞ 2 A m -x=m 3 yH 2 O

Experimental and density functional theory (DFT) studies are described that are focused on outlining the reactivity of the known photochemical nitric oxide precursor trans-Cr(cyclam)(ONO)(2)(+) ("CrONO", cyclam = 1,4,8,11-tetrazacycltetradecane). Studies in both aerated and deaerated aqueous media are described as are the roles of both the oxidant O(2) and a reductant such as glutathione in trapping the apparent Cr(IV) photoreaction intermediate trans-Cr(cyclam)(O)(ONO)(+). Also reported and characterized structurally is the Cr(V) product of long-term photolysis in the absence of reducing agents, the trans-dioxo species [trans-Cr(cyclam)(O)(2)](ClO(4)). Photosensitization experiments indicate that at least a significant fraction of the reaction occurs from the lowest energy doublet excited state(s). Lastly, cell culture experiments demonstrate that CrONO has little or no acute toxicity either before or after photolysis.