Tin-containing zeolites are highly active catalysts for the isomerization of glucose in water

The isomerization of glucose into fructose is a large-scale reaction for the production of high-fructose corn syrup (HFCS; reaction performed by enzyme catalysts) and recently is being considered as an intermediate step in the possible route of biomass to fuels and chemicals. Here, it is shown that a large-pore zeolite that contains tin (Sn-Beta) is able to isomerize glucose to fructose in aqueous media with high activity and selectivity. Specifically, a 10% (wt/wt) glucose solution containing a catalytic amount of Sn-Beta (1∶50 Sn:glucose molar ratio) gives product yields of approximately 46% (wt/wt) glucose, 31% (wt/wt) fructose, and 9% (wt/wt) mannose after 30 min and 12 min of reaction at 383 K and 413 K, respectively. This reactivity is achieved also when a 45 wt% glucose solution is used. The properties of the large-pore zeolite greatly influence the reaction behavior because the reaction does not proceed with a medium-pore zeolite, and the isomerization activity is considerably lower when the metal centers are incorporated in ordered mesoporous silica (MCM-41). The Sn-Beta catalyst can be used for multiple cycles, and the reaction stops when the solid is removed, clearly indicating that the catalysis is occurring heterogeneously. Most importantly, the Sn-Beta catalyst is able to perform the isomerization reaction in highly acidic, aqueous environments with equivalent activity and product distribution as in media without added acid. This enables Sn-Beta to couple isomerizations with other acid-catalyzed reactions, including hydrolysis/isomerization or isomerization/dehydration reaction sequences [starch to fructose and glucose to 5-hydroxymethylfurfural (HMF) demonstrated here]

One-pot synthesis of MWW zeolite nanosheets using a rationally designed organic structure-directing agent

A new material MIT-1 comprised of delaminated MWW zeolite nanosheets is made in a one-pot synthesis using a rationally designed organic structure-directing agent (OSDA). The OSDA consists of a hydrophilic head segment that resembles the OSDA used to synthesize the zeolite precursor MCM-22(P), a hydrophobic tail segment that resembles the swelling agent used to swell MCM-22(P), and a di-quaternary ammonium linker that connects both segments. MIT-1 features high crystallinity and surface areas exceeding 500 m[superscript 2] g[superscript −1], and can be synthesized over a wide synthesis window that includes Si/Al ratios ranging from 13 to 67. Characterization data reveal high mesoporosity and acid strength with no detectable amorphous silica phases. Compared to MCM-22 and MCM-56, MIT-1 shows a three-fold increase in catalytic activity for the Friedel–Crafts alkylation of benzene with benzyl alcohol.United States. Dept. of Energy. Office of Basic Energy Sciences. Chemical Sciences, Geosciences, & Biosciences Division (DE-FG0212ER16352)Natural Sciences and Engineering Research Council of Canada (Banting Postdoctoral Fellowship

Conversion of glucose to lactic acid derivatives with mesoporous Sn-MCM-41 and microporous titanosilicates

BACKGROUND: The production of value-added products from biomass has acquired increasing importance due to the high worldwide demand for chemicals and energy, uncertain petroleum availability and the necessity of finding environmentally friendly processes. This paper reports work on the synthesis of several catalysts for the conversion of glucose to methyl lactate. RESULTS: A MCM-41 type mesoporous material containing tin (Si/Sn = 55) was developed with a uniform ordered mesoporous structure, high specific surface area and high pore volume. Sn-MCM-41 was tested in three consecutive catalytic cycles to evaluate its reusability giving methyl lactate yields of 43%, 41% and 39%, in each cycle. The slightly reduction in activity could be explained by the reduction in the accessibility of active centers due to the adsorption of reaction products and structural changes. Microporous titanosilicates and MFI-type zeolite ZSM-5 showed a lower catalytic performance, but exfoliated materials gave higher yields of methyl lactate and pyruvaldehyde dimethyl acetal than their respective layered precursors. CONCLUSIONS: Sn-MCM-41 material showed good results in the conversion of glucose to methyl lactate over three catalytic cycles and exfoliated materials facilitated the access of glucose to the catalytic sites and fast desorption of products.The authors gratefully thank the Spanish Ministry of Economy and Competitiveness (MINECO) for financial support through project MAT2010-15870, as well as the Regional Government of Aragón (DGA), the Obra Social La Caixa (GA-LC-019/2011) and the European Social Fund (ESF). C. Casado also thanks MINECO for the ‘Ramón y Cajal’ program (RYC-2011-08550)

From Biomass-Derived Furans to Aromatics with Ethanol over Zeolite

We report anovel catalytic conversion of biomass-derived furans and alcohols to aromatics over zeolite catalysts.Aromatics are formed via Diels–Alder cycloaddition withethylene,whichisproduced in situ from ethanol dehydration.The use of liquid ethanol instead of gaseous ethylene,asthesource of dienophile in this one-pot synthesis,makes thearomatics production muchsimpler and renewable,circum-venting the use of ethylene at high pressure.More importantly,both our experiments and theoretical studies demonstrate thatthe use of ethanol instead of ethylene,results in significantlyhigher rates and higher selectivity to aromatics,due to loweractivation barriers over the solid acid sites.Synchrotron-diffraction experiments and proton-affinity calculations clearlysuggest that apreferred protonation of ethanol over the furan isakey step facilitating the Diels–Alder and dehydrationreactions in the acid sites of the zeolite

Biomass Production Potential of a Wastewater Alga Chlorella vulgaris ARC 1 under Elevated Levels of CO2 and Temperature

The growth response of Chlorella vulgaris was studied under varying concentrations of carbon dioxide (ranging from 0.036 to 20%) and temperature (30, 40 and 50°C). The highest chlorophyll concentration (11 μg mL–1) and biomass (210 μg mL–1), which were 60 and 20 times more than that of C. vulgaris at ambient CO2 (0.036%), were recorded at 6% CO2 level. At 16% CO2 level, the concentrations of chlorophyll and biomass values were comparable to those at ambient CO2 but further increases in the CO2 level decreased both of them. Results showed that the optimum temperature for biomass production was 30°C under elevated CO2 (6%). Although increases in temperature above 30°C resulted in concomitant decrease in growth response, their adverse effects were significantly subdued at elevated CO2. There were also differential responses of the alga, assessed in terms of NaH14CO3 uptake and carbonic anhydrase activity, to increases in temperature at elevated CO2. The results indicated that Chlorella vulgaris grew better at elevated CO2 level at 30°C, albeit with lesser efficiencies at higher temperatures

Oriented 2.0.0 Cu2O nanoplatelets supported on few-layers graphene as efficient visible light photocatalyst for overall water splitting

[EN] Cu2O nanoplatelets with preferential 2.0.0 facet orientation supported on few layers graphene were prepared as films in a single step by pyrolysis at 900 degrees C under inert atmosphere of Cu2+-chitosan precursor. (Cu2O) over bar /fl-G films exhibit a photocatalytic activity for overall water splitting of 19.5 mmol/g(cu+G) h. This value is about 4 orders of magnitude higher than the photocatalytic activity measured for unoriented Cu2O nanoparticles on few-layers graphene or than commercial Cu2O nanoparticles and about three orders of magnitude higher than the activity reported in the literature for Cu2O nanoparticles. In addition Cu2O nanoparticles on few-layers graphene retain about 50% of its photocatalytic activity after 6 days of continuous irradiation. It is proposed that this activity and stability arises from the combination of features derived from the pyrolysis preparation procedure including strong Cu2O-graphene grafting, the role of graphene as cocatalyst and preferential 2.0.0 facet orientation. (C) 2016 Elsevier B.V. All rights reserved.Finantial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2015-69153-CO2-1-R) and Generalitat Valenciana (Prometeo 2013-019) is gratefully acknowledged. D. M. M. and I. E. A thank to the Technical University of Valencia and the Spanish Ministry of Science for PhD scholarshipsMateo-Mateo, D.; Esteve-Adell, I.; Albero-Sancho, J.; Primo Arnau, AM.; García Gómez, H. (2017). Oriented 2.0.0 Cu2O nanoplatelets supported on few-layers graphene as efficient visible light photocatalyst for overall water splitting. Applied Catalysis B Environmental. 201:582-590. https://doi.org/10.1016/j.apcatb.2016.08.033S58259020

A Bio-Catalytic Approach to Aliphatic Ketones

Depleting oil reserves and growing environmental concerns have necessitated the development of sustainable processes to fuels and chemicals. Here we have developed a general metabolic platform in E. coli to biosynthesize carboxylic acids. By engineering selectivity of 2-ketoacid decarboxylases and screening for promiscuous aldehyde dehydrogenases, synthetic pathways were constructed to produce both C5 and C6 acids. In particular, the production of isovaleric acid reached 32 g/L (0.22 g/g glucose yield), which is 58% of the theoretical yield. Furthermore, we have developed solid base catalysts to efficiently ketonize the bio-derived carboxylic acids such as isovaleric acid and isocaproic acid into high volume industrial ketones: methyl isobutyl ketone (MIBK, yield 84%), diisobutyl ketone (DIBK, yield 66%) and methyl isoamyl ketone (MIAK, yield 81%). This hybrid “Bio-Catalytic conversion” approach provides a general strategy to manufacture aliphatic ketones, and represents an alternate route to expanding the repertoire of renewable chemicals

Conversion of biomass platform molecules into fuel additives and liquid hydrocarbon fuels

[EN] In this work some relevant processes for the preparation of liquid hydrocarbon fuels and fuel additives from cellulose, hemicellulose and triglycerides derived platform molecules are discussed. Thus, it is shown that a series of platform molecules such as levulinic acid, furans, fatty acids and polyols can be converted into a variety of fuel additives through catalytic transformations that include reduction, esterification, etherification, and acetalization reactions. Moreover, we will show that liquid hydrocarbon fuels can be obtained by combining oxygen removal processes (e.g. dehydration, hydrogenolysis, hydrogenation, decarbonylation/descarboxylation etc.) with the adjustment of the molecular weight via C C coupling reactions (e.g. aldol condensation, hydroxyalkylation, oligomerization, ketonization) of the reactive platform molecules.This work has been supported by the Spanish Government-MINECO through Consolider Ingenio 2010-Multicat and CTQ.-2011-27550, ITQ thanks the "Program Severo Ochoa" for financial support.Climent Olmedo, MJ.; Corma Canós, A.; Iborra Chornet, S. (2014). Conversion of biomass platform molecules into fuel additives and liquid hydrocarbon fuels. Green Chemistry. 16(2):516-547. https://doi.org/10.1039/c3gc41492bS51654716