Density Functional Theory Investigation for Catalytic Mechanism of Gasoline Alkylation Desulfurization over NKC‑9 Ion-Exchange Resin

The molecular level understanding of the mechanism about the 3-methylthiophene (3MT) alkylation with isobutylene (IB) as well as the side reaction of IB dimerization over NKC-9 cation exchange resin has been investigated using the density functional theory (DFT) of quantum chemical method. A model of benzene sulfonic acid was used to represent the cation-exchange resin catalyst. Two different reaction mechanism typesstepwise scheme and concerted scheme have been evaluated. Activation energies of each reaction path which were obtained from the DFT results have been improved by single-point MP2 calculations. In the stepwise mechanism, both 3MT alkylation and IB dimerization proceed by adsorption and protonation of the IB to form a sulfonic ester intermediate, and then by C–C bond formation between the sulfonic ester intermediate and another 3MT or IB to give the reaction products. The second step is rate-determining and has activation barriers of 148.41 kJ/mol for 3MT alkylation and 160.52 kJ/mol for IB dimerization. In the concerted mechanism, the reaction occurs in one step of simultaneous protonation and C–C bond formation. The activation barrier is calculated to be 169.10 kJ/mol for 3MT alkylation, and that for IB dimerization is 174.02 kJ/mol. The results revealed that the reaction mechanism of 3MT alkylation was very similar to that of IB dimerization, and the stepwise mechanism dominated both the 3MT alkylation and IB dimerization. Moreover, 3MT alkylation is more easily occurs than IB dimerization during gasoline alkylation desulfurization

Upgrading Ethanol to Higher Alcohols via Biomass-Derived Ni/Bio-Apatite

Acquiring value-added chemicals from renewable ethanol instead of fossil resources has special significance under the background of carbon neutrality. In this work, a heterogeneous recyclable biomass-derived Ni/bio-apatite catalyst was developed for upgrading ethanol to higher alcohols (C6+-OH). Catalysts were prepared employing calcined porous natural bone and analyzed by various characterizations of thermogravimetric analysis–differential thermal analysis, X-ray diffraction, high-angle annular dark field scanning transmission electron microscopy, X-ray photoelectron spectroscopy, H2-temperature-programmed reduction, and CO2-temperature-programmed desorption. The ethanol upgrading reaction can be achieved in the liquid phase without alkali additives, ligands, and extra hydrogen. The selectivity for C6+-OH reached as high as 67.7% at the single pass 55.6% ethanol conversion, substantially higher than the Anderson–Schulz–Flory distribution. Research shows that the porous structure and coordination between metal and alkaline sites could play key roles in C6+-OH selectivity. The catalyst recycles and reaction pathway of ethanol upgrading to higher alcohols were also discussed

Synthesis and Characterization of Functionalized Ionic Liquids for Thermal Storage

A series of imidazolium-based ionic liquids were synthesized by introducing functional groups in the imidazolium cation to develop new phase change materials. The structures of these ionic liquids were determined by nuclear magnetic resonance; the quantum calculation was performed based on density functional theory by Gaussian 09 to determine the number of hydrogen bonds among the ions. The heat of fusion, heat capacity, and thermal storage density of the ionic liquids were investigated by DSC; in addition, the thermal stability was determined by TGA. The thermal analysis results indicate that new functionalized ionic liquids have excellent thermal stability with decomposition temperatures higher than 475 K. In addition, the heat of fusion, heat capacity, and thermal storage density of the functionalized ionic liquids increased on average by 34, 86.5, and 100%, respectively, compared with alkyl chain ionic liquids with the same carbon numbers. These superior properties are attributed to the additional hydrogen bonds in the functionalized ionic liquids

Additional file 1 of Unravel the regulatory mechanism of Yrr1p phosphorylation in response to vanillin stress in Saccharomyces cerevisiae

Additional file 1: Table S1. Yeast strains used in this study. Table S2. List of primers used for plasmids and strain construction in this work. Figure S1. Growth curve of all eleven point mutants under 6 mM vanillin stress in SC-Ura medium. The error bar represents three times the standard deviation. Figure S2. Resistance test of recombinant strains. The host strains were all BY4741. Incubate in SC-Ura liquid medium supplemented with 12 mM furfural (a), 20 mM HMF (b) and no inhibitor (c) at 30℃. The error bar represents three times the standard deviation. Figure S3. Resistance test of recombinant strains. The host strains were all BY4741. Incubate in SC-Ura liquid medium supplemented with 0.05 mg L-1 4NQO at 30℃. The error bar represents three times the standard deviation. Figure S4. Subcellular localization of two site phosphorylation and dephosphorylation mutations. The samples were cultured in SC-Ura. Intracellular localization was analyzed by fluorescence microscope (green). Nuclear DNA was stained with DAPI (blue). Figure S5. Subcellular localization of two site phosphorylation and dephosphorylation mutations. The samples were cultured in SC-Ura. Intracellular localization was analyzed by fluorescence microscope (green). Nuclear DNA was stained with DAPI (blue)

High-Performance Carbon Molecular Sieve Membrane Derived from a Crown Ether-Containing Co-Polyimide Precursor for Gas Separation

A carbon molecular sieve (CMS) membrane was prepared via a co-polyimide precursor containing a crown ether segment. Two elements ensured that the CMS membrane achieved both high permeability and selectivity: (1) preferential decomposition of the crown ether segment at relative low temperature and (2) the transformation of a pore structure from a micropore (>7 Å) to an ultra-micropore (<7 Å) at a higher-temperature pyrolysis. A BET analysis showed the CMS membrane formed a micropore below 500 °C. Then, the micropore structure gradually transformed to an ultra-micropore when the heat-treatment temperature raised to 500 and 650 °C, followed by formation of a single-distribution ultra-micropore pyrolyzed at 800 °C. The performance of membranes treated at 650 and 800 °C surpassed the 2015 upper bound for H2 separation and the 2019 upper bound for CO2 separation. Furthermore, the membrane treated at 650 °C exhibited remarkable mixed-gas separation performance and possessed a CO2 permeability of 7266.4 ± 22.85 to 7496.3 ± 22.34 barrer and a CO2/N2 (20/80, vol%) and CO2/CH4 (10/90, vol%) selectivity of ∼60

NO Catalytic Reduction on Urea-Loaded Ferromanganese Catalysts: Performance, Characterization, and Mechanism

As one of the important atmospheric pollutants, the removal of NO in flue gas at low temperatures is still a severe challenge. Selective catalytic reduction (SCR) with urea is an effective method for NO removal at low temperatures. Herein, through directly loading urea, an Fe-modified Mn-based molecular sieve catalyst with good low-temperature urea-SCR activity was prepared by a stepwise impregnation method. The results show that with a mass ratio of Mn/Fe of 10:0.5 and a calcination temperature of 500 °C, the catalyst loaded with 15 wt % urea had the highest catalytic activity of 98.5% at 250 °C. Online mass spectrometry results show that NH3 formed from the decomposition of urea reacts with NO when the temperature is above 150 °C, while urea directly reacts with NO below 150 °C. The density functional theory calculation demonstrates that the doping of Fe weakens the strength of the Mn–O bond in MnO2, which makes NO easier to combine with lattice oxygen to oxidize into NO2, thereby promoting the whole urea-SCR reaction. This work provides an overall perspective and theoretical support for the design of urea-SCR catalysts over a wide temperature range

Chemical Looping Reforming of Toluene as Volatile Model Compound over LaFe_<i>x</i>M_1–<i>x</i>O₃@SBA via Encapsulation Strategy

Aiming at the problems of large tar influence and low gasification efficiency in traditional biomass gasification, in this paper, a chemical looping reforming (CLR) of volatiles from biomass pyrolysis based on decoupling strategy is proposed to convert macromolecular volatiles into hydrogen-rich syngas. A series of highly active and selective oxygen carrier (OC) SBA-15 encapsulating LaFexM1–xO3 (M = Ni, Cu, Co) for the biomass CLR process was developed. Reaction kinetics and cycling performance of toluene CLR process on LaFe0.6Co0.4O3@SBA-15 OCs were explored. Experimental results showed that the encapsulation effect gave the metal oxide a better dispersion, reduced the sintering, and improved the reaction performance. Compared with LaFeO3, the toluene conversion increased from 52.3% to 79.7%, the CO selectivity improved from 57.0% to 87.4%, and the oxygen release (OR) increased by 100% after encapsulation in SBA-15. Due to the substitution of Ni2+, Cu2+ and Co2+ on Fe3+, more oxygen vacancies in OCs were created, and both conversions of toluene and selectivity of CO were improved. Among them, the incorporation of Co had the best performance, the toluene conversion was 81.6%, and the CO selectivity was 96.8%. The kinetics of the LaFe0.6Co0.4O3@SBA-15 reaction was solved using a gas–solid reaction model with an activation energy of 103.9 kJ mol–1 and a pre-exponential factor of 123.8 s–1. The performance of LaFe0.6Co0.4O3@SBA-15 was tested for 10 cycles, and it was found that conversion of toluene and CO selectivity were well-maintained at 90.0%–92.0% and 93.0%–96.0%, respectively. This study could guide the selection of OCs in reforming macromolecular volatiles from biomass pyrolysis to produce hydrogen-rich syngas

Boosting Photocatalytic Nitrogen Fixation via Constructing Low-Oxidation-State Active Sites in the Nanoconfined Spinel Iron Cobalt Oxide

The achievement of both N2 enrichment and activation of NN bonds on active sites in the photocatalytic nitrogen reduction reaction (NRR) under environmental conditions is a long-sought-after goal. Here, a nanoconfined spinel iron cobalt oxide (FeCo2O4) is prepared, which has a low oxidation state and stronger Fe’s 3d orbital electron-donating capability of iron active sites and can efficiently transfer electrons to N2 π* orbitals to facilitate activation of nitrogen. Additionally, we rationally control the mass transfer of nitrogen molecules in a nanoconfined interior cavity via the nanoconfined effect, forcing the N2 enrichment in the iron cobalt oxide semiconductor. In this work, the NRR performance of the nanoconfined iron cobalt oxide photocatalyst achieves 1.26 μmol h–1 (10 mg of photocatalyst addition), which is 3.7 times higher than that of bulk FeCo2O4. Our proposed strategy simultaneously satisfies both N2 capture and activation of nitrogen and instructs the development of low-oxidation-state iron-based photocatalysts for nitrogen fixation