@article { ISI:000326320000017, title = {Efficient, stable, and reusable silicoaluminophosphate for the one-pot production of furfural from hemicellulose}, journal = {ACS Catalysis}, volume = {3}, number = {10}, year = {2013}, month = {OCT}, pages = {2299-2303}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Development of stable, reusable, and water tolerant solid acid catalysts in the conversion of polysaccharides to give value-added chemicals is vital because catalysts are prone to undergo morphological changes during the reactions With the anticipation that silicoaluminophosphate (SAPO) catalysts will have higher hydrothermal stability, those were synthesized, characterized, and employed in a one-pot conversion of hemicellulose. SAPO-44 catalyst at 170 degrees C within 8 h could give 63\% furfural yield with 88\% mass balance and showed similar activity up to at least 8 catalytic cycles. The morphological studies revealed that SAPO catalysts having hydrophilic characteristics are stable under reaction conditions.

}, keywords = {furfural, Hemicellulose, hydrophilicity, SAPO, water-tolerant catalyst, zeolite}, issn = {2155-5435}, doi = {10.1021/cs400495j}, author = {Bhaumik, Prasenjit and Dhepe, Paresh Laxmikant} } @article { ISI:000325272100040, title = {Influence of properties of SAPO{\textquoteright}s on the one-pot conversion of mono-, di- and poly-saccharides into 5-hydroxymethylfurfural}, journal = {RSC Advances}, volume = {3}, number = {38}, year = {2013}, month = {JUL}, pages = {17156-17165}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Synthesis of 5-hydroxymethylfurfural (5-HMF) from biomass derived mono-and poly-saccharides is gaining importance because of its usefulness in the preparation of important chemicals. In our work, we have synthesized several silicoaluminophosphate (SAPO) catalysts, and have shown that in the absence of any other pH modifying reagents, those are active in converting mono-and poly-saccharides into 5-HMF under biphasic reaction condition at 175 degrees C. Particularly, SAPO-44 catalyst showed the best activity in the conversion of fructose to yield 78\% 5-HMF with 88\% selectivity. On the contrary, all other catalysts showed lower yields (H-MOR: 63\%, SAPO-5: 32\%, 2DCT: 60\%). Over SAPO-44, good yields for 5-HMF were observed when glucose (67\%), maltose (57\%), cellobiose (56\%) and starch (68\%) were used as substrates. Recycle study carried out with SAPO-44 catalyst in the fructose conversion reaction showed marginal decrease in the activity up to 3rd run and then afterwards constant activity was observed up to 5th run (1st: 78\%, 2nd: 71\%, 3rd: 66\%, 4th: 65\%, 5th: 65\%). Catalyst characterizations revealed that SAPO catalysts have higher hydrophilic nature than H-MOR (Si/Al = 10) and hence it is postulated that this property may help in achieving better results. Further studies on the catalyst characterizations revealed that SAPO-44 undergoes modifications in its structure. However, ICP-OES data suggests that Al and/or P are not leached out in the solution indicating that change in local environment around elements is possible. The influence of acid amount, type of acid site etc. on the catalytic activity is discussed and found out that strong acid sites are required to boost the 5-HMF yields.

}, issn = {2046-2069}, doi = {10.1039/c3ra43197e}, author = {Bhaumik, Prasenjit and Dhepe, Paresh Laxmikant} } @article { ISI:000338434800028, title = {Exceptionally high yields of furfural from assorted raw biomass over solid acids}, journal = {RSC Advances}, volume = {4}, number = {50}, year = {2014}, month = {MAY}, pages = {26215-26221}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Development of stable and recyclable solid acid catalysts in the efficient valorisation of hemicellulose to yield C-5 sugars and furfural is vital to boost the prospects of using lignocelluloses for chemicals synthesis. Using an silicoaluminophosphate, namely SAPO-44, as a catalyst, an environmentally benign process of furfural synthesis from diversified real substrates (without any treatment or the need for separation of its components) is shown. In an efficient one-pot methodology, at 443 K and in the presence of a biphasic solvent system, selective conversions of hemicelluloses from raw biomass (bagasse, rice husk and wheat straw) to extraordinarily high yields of furfural of about 93\% were attainable. Under similar reaction conditions, an 82\% yield of furfural is also achievable directly from isolated hemicellulose within 10 h. Hydrophilic SAPO-44, having higher hydrothermal stability, showed similar activity for all the substrates for a minimum of up to 8 times in recycling runs. Various physicochemical characterizations (X-ray diffraction, thermogravimetric analysis-derivative thermogravimetry, temperature programmed desorption-NH3, N-2 sorption, solid-state nuclear magnetic resonance spectroscopy) of fresh and spent catalysts were used to improve SAPO-44 stability.

}, issn = {2046-2069}, doi = {10.1039/c4ra04119d}, author = {Bhaumik, Prasenjit and Dhepe, Paresh Laxmikant} } @article { ISI:000340208400016, title = {Silica and zirconia supported tungsten, molybdenum and gallium oxide catalysts for the synthesis of furfural}, journal = {Catalysis Science \& Technology}, volume = {4}, number = {9}, year = {2014}, month = {JUN}, pages = {2904-2907}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

SiO2 and ZrO2 supported W, Mo and Ga oxide catalysts were prepared by a sol-gel and wet-impregnation method. The 10 wt\% WO3/SiO2 (sol-gel) catalyst showed 61 +/- 2\% furfural yield from hemicellulose in a one-pot fashion for at least 8 cycles. Based on XRD, TPD and Hammett acidity characterizations, the catalyst structure-activity correlation was drawn.

}, issn = {2044-4753}, doi = {10.1039/c4cy00530a}, author = {Bhaumik, Prasenjit and Kane, Tanushree and Dhepe, Paresh Laxmikant} } @article { ISI:000334895800008, title = {Value addition to lignocellulosics and biomass-derived sugars: an insight into solid acid-based catalytic methods}, journal = {Journal of Chemical Sciences}, volume = {126}, number = {2, SI}, year = {2014}, note = {21st National Symposium on Catalysis (CATSYMP), CSIR Indian Inst Chem Technol, Hyderabad, INDIA, FEB 11-13, 2013}, month = {MAR}, pages = {373-385}, publisher = {Catalysis Soc India}, type = {Article, Proceedings Paper}, address = {C V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIA}, abstract = {

For the synthesis of important platform chemicals such as sugars (xylose and arabinose) and furans (furfural and 5-hydroxymethylfurfural (HMF)) from carbohydrates (hemicellulose and fructose) solid acid catalysts are employed. Similarly, over solid acid catalysts, conversion of lignin into aromatic monomers is performed. It is observed that in the dehydration of fructose, because of higher hydrothermal stability, silicoaluminophosphate (SAPO) catalysts give better activity (78\% HMF yield) compared with other solid acid catalysts (\<63\% HMF yield) at 175 degrees C. Particularly, SAPO-44 catalyst can be reused at least 5 times with marginal decrease in the activity. Zeolite, BUSY (Si/Al = 15) is active in the conversion of isolated (pure) hemicellulose to produce 41\% C-5 sugars in water. The catalyst is also active in the selective conversion of hemicellulose from bagasse to yield 59\% C-5 sugars. It is possible to obtain high yields of furfural (54\%) directly from bagasse if instead of water, Water+toluene solvent system is used. Depolymerization of lignin using HUSY catalyst produced aromatic monomers with 60\% yield at 250 degrees C. A detailed catalyst characterization study is performed to understand the correlation between catalyst activity and morphology. To understand the effect of impurities present in the substrate over solid acid catalysts, metal-exchange study is carried out.

}, keywords = {aromatic monomers, Biomass, furans, Hemicellulose, lignin, solid acid catalyst}, issn = {0974-3626}, author = {Bhaumik, Prasenjit and Deepa, Ayillath K. and Kane, Tanushree and Dhepe, Paresh Laxmikant} } @inbook {42953, title = {Conversion of biomass into sugars}, booktitle = {Biomass sugars for non-fuel applications}, year = {2015}, pages = {1-53}, publisher = {Royal Society of Chemistry}, organization = {Royal Society of Chemistry}, chapter = {1}, address = {Cambridge, UK}, doi = {10.1039/9781782622079}, author = {Bhaumik, Prasenjit and Dhepe, Paresh Laxmikant and Dmitry, Murzin and Olga, Simakova} } @article { ISI:000354137000012, title = {Effects of careful designing of SAPO-44 catalysts on the efficient synthesis of furfural}, journal = {Catalysis Today}, volume = {251}, year = {2015}, note = {7th Tokyo Conference on Advanced Catalytic Science and Technology (TOCAT), Kyoto, JAPAN, JUN 01-06, 2014}, month = {AUG}, pages = {66-72}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Considering the growing importance of furfural, it is necessary to develop a robust solid acid catalyst for the conversion of xylan (hemicelluloses) into furfural in a one-pot method. In this study, the effects of various components (Si, Al and P) and crystallization time on the preparation of acidic materials and their properties are extensively described. It is seen that with the increase in crystallization time (0, 48, 96, 176 h) during the synthesis of silicoaluminophosphate (SAPO-44), materials morphology changes from amorphous to AFI to CHA and the best activity for furfural synthesis (82\%) from xylan was observed with SAPO-44 catalyst aged for 176 h. Since, acidity in the SAPO-44 is guided by the incorporation of Si in the ALPO framework, study on Si molar concentration (0.8, 1.0, 1.2, 1.4 and 1.6) in SAPO-44 was carried out and it was observed that SAPO-44 having 1.0 mole of Si content is the best catalyst for the xylan/xylose conversion to furfural. Catalyst structure-activity correlation is thoroughly defined with the help of several physico-chemical properties. (C) 2014 Elsevier B.V. All rights reserved.

}, keywords = {Biomass, furfural, Hemicellulose, SAPO-44, Xylose}, issn = {0920-5861}, doi = {10.1016/j.cattod.2014.10.042}, author = {Bhaumik, Prasenjit and Dhepe, Paresh Laxmikant} } @article { ISI:000370664300002, title = {Solid acid catalyzed synthesis of furans from carbohydrates}, journal = {Catalysis Reviews-Science and Engineering}, volume = {58}, number = {1}, year = {2016}, month = {JAN}, pages = {36-112}, publisher = {TAYLOR \& FRANCIS INC}, type = {Article}, address = {530 WALNUT STREET, STE 850, PHILADELPHIA, PA 19106 USA}, abstract = {

The alternative feedstock, biomass (particularly lignocelluloses), having the profuse availability, is promising for the synthesis of several value-added chemicals which are currently obtained from fossil feedstock. In this article, the synthesis of two extremely significant furan chemicals viz. furfural and 5-hydroxymethylfurfural (HMF) are discussed. In the synthesis of furans from biomass, numerous challenges, i.e., use of edible sugars as substrates, selectivity to furans, their isolation in pure form, reuse of catalyst, environmental issues, etc., are perceived and in the recent past researchers tried to resolve those by developing advance methodologies. This article comprehensively summarizes the latest progress made in the above-mentioned areas and also provides commentary on the analyses of results, rationale for observed activity and mechanisms, etc. It also discusses future aspects of this work.

}, keywords = {Biomass conversion, carbohydrates, cellulose, furans, furfural, hemicelluloses, HMF, solid acid catalyst}, issn = {0161-4940}, doi = {10.1080/01614940.2015.1099894}, author = {Bhaumik, Prasenjit and Dhepe, Paresh Laxmikant} } @article {42948, title = {From lignocellulosic biomass to furfural: insight into the active species of a silica-supported tungsten oxide catalyst}, journal = {ChemCatChem}, volume = {9}, year = {2017}, month = {JUL}, pages = {2709-2716}, type = {Article}, abstract = {

A sol{\textendash}gel-synthesized silica-supported tungsten oxide catalyst that has Lewis acidity was characterized and employed as a solid acid catalyst in the synthesis of furfural directly from lignocellulosic biomass (isolated xylans and crop wastes). In a one-pot method, 71 \% furfural formation from isolated xylan was possible using a water/toluene (1:2 v/v) biphasic solvent system at 170 {\textdegree}C after 10 h over 10 wt \% WO3/SiO2. The WO3/SiO2 catalyst in the selective conversion of pentosan from crop wastes (bagasse, wheat straw, and rice husk) yielded 72{\textendash}87 \% furfural under the optimum reaction conditions. Additionally, the catalyst presented excellent recyclability in at least eight runs after simple water washing. From the catalyst characterization studies, it was suggested that silicotungstic-type acid species are anchored on the WO3/SiO2 catalyst that help to achieve a good catalytic activity.

}, doi = {10.1002/cctc.201600784}, author = {Bhaumik, Prasenjit and Dhepe, Paresh Laxmikant} }