Formation and Growth of Humins via Aldol Addition and Condensation during Acid-Catalyzed Conversion of 5-Hydroxymethylfurfural

Patil, Sushil K. R.; Lund, C.R.F.

doi:10.1021/ef2010157

Cited by 491 publications

(543 citation statements)

References 39 publications

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“…[15] To summarize, the HMF selectivity had an early linear correlation with L*/L but exhibited av olcano-type curve with B/L. However,m edium-to-strong Lewis acid sites were favorable for the formation of LA and humins, which therebyr educed the HMF selectivity.T ov erify these findings,N bO x sites were added to AlSiO to adjust the acidity because of the hydrothermal stability of Nb 2 O 5 , [16] and the product was used in the conversion of glucoseinto HMF.…”

Section: Effect Of the Acidity On The Selectivity To Hmfla And Huminsmentioning

confidence: 87%

Comprehensive Understanding of the Role of Brønsted and Lewis Acid Sites in Glucose Conversion into 5‐Hydromethylfurfural

Peng

Liu

et al. 2017

ChemCatChem

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The conversion of glucose and selectivity into 5‐hydromethylfurfural (HMF) were investigated over various silica–alumina composite (AlSiO) catalysts. The type, amount, and strength of the acidic sites were characterized by using NH3 temperature‐programmed desorption and FTIR spectroscopy and then correlated to the catalytic conversion of glucose into HMF to provide a quantitative relationship between the acidity and product selectivity. Lewis acid sites played an important role in glucose conversion, which can enhance the isomerization of glucose to fructose, whereas Brønsted acid sites had a detrimental effect. HMF selectivity had an almost linear relationship with the weak/total Lewis acid ratio (L*/L), indicating that weak Lewis acids could promote formation of HMF. The medium‐to‐strong Lewis acid sites can enhance the formation of undesired byproducts (levulinic acid, humins). The Brønsted to Lewis acid ratio (B/L) had an influence on the HMF selectivity; at similar L*/L ratios, volcano curves were obtained with the increase of the B/L ratio, but the influence was not as great as that of the L*/L ratio. Nb‐doped AlSiO catalysts were prepared and used in the conversion of glucose into HMF, which also confirmed the above findings. Under the optimized conditions, the HMF selectivity can reach 71 % at 92.6 % conversion of glucose with no clear decline after four catalytic cycles.

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Section: Effect Of the Acidity On The Selectivity To Hmfla And Huminsmentioning

confidence: 87%

Comprehensive Understanding of the Role of Brønsted and Lewis Acid Sites in Glucose Conversion into 5‐Hydromethylfurfural

Peng

Liu

et al. 2017

ChemCatChem

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“…Once 5-HMF is formed, it is in situ "polymerised" yielding the HTC carbon product [8]. While most of the research efforts focus on the exploitation of HMF for the production of chemicals, bioplastics and biofuels [9], the Titirici´s group rediscovered these processes for the production of green and valuable carbon and carbon-hybrid materials [1,4].…”

Section: Introductionmentioning

confidence: 99%

Tailoring the porosity of chemically activated hydrothermal carbons: Influence of the precursor and hydrothermal carbonization temperature

Falco

Marco-Lozar

Salinas-Torres

et al. 2013

Carbon

213

131

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Advanced porous materials with tailored porosity (extremely high development of microporosity together with a narrow micropore size distribution (MPSD)) are required in energy and environmental related applications. Lignocellulosic biomass derived HTC carbons are good precursors for the synthesis of activated carbons (ACs) via KOH chemical activation. However, more research is needed in order to tailor the microporosity for those specific applications. In the present work, the influence of the precursor and HTC temperature on the porous properties of the resulting ACs is analyzed, remarking that, regardless of the precursor, highly microporous ACs could be generated. The HTC temperature was found to be an extremely influential parameter affecting the porosity development and the MPSD of the ACs. Tuning of the MPSD of the ACs was achived by modification of the HTC temperature. Promising preliminary results in gas storage (i.e. CO 2 capture and high pressure CH 4 storage) were obtained with these materials, showing the effectiveness of this synthesis strategy in converting a low value lignocellulosic biomass into a functional carbon material with high performance in gas storage applications. IntroductionHydrothermal Carbonization (HTC) is now a well-established thermochemical synthesis alternative to produce functional carbon materials with a tunable chemical structure from pure carbohydrates or lignocellulosic biomass [1][2][3].During HTC, biomass-derived precursors are converted into valuable carbon materials using water as reaction medium at mild temperatures (< 200°C) under self-generated pressures [4]. Even though this methodology has been known for almost 100 years [5], its full potential, as a synthetic route for carbon materials having important applications in several fields such as catalysis, energy storage, CO 2 sequestration, water purification, soil remediation, has been revealed only recently, mainly via the work of Dr. Titirici and coworkers [6].Under hydrothermal conditions monosaccharides are dehydrated to 5-hydroxymethylfurfural (5-HMF) via the well-known Lobry de Bruyn-Alberta van Ekstein rearrangement [7]. Once 5-HMF is formed, it is in situ "polymerised" yielding the HTC carbon product [8]. While most of the research efforts focus on the exploitation of HMF for the production of chemicals, bioplastics and biofuels [9], the Titirici´s group rediscovered these processes for the production of green and valuable carbon and carbon-hybrid materials [1,4].One of the main limiting factors, hindering the effective and straightforward exploitation of HTC carbons for several end-applications (eg. catalysis, separation science, energy production and storage), is their low surface area and porosity [10]. In the case of monosaccharide derived HTC carbons, this problem has been elegantly overcome by using hard\soft-templating strategies or by addition of structural directing agents [11][12][13]. Such synthetic routes are effective because of the homogeneous nature of the pre-HTC aqueous reaction mixt...

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“…Carbohydrates may produce humins via reversion [29]. The 5-HMF reaction without carbohydrates might form humins by aldol condensation mechanism with following water elimination [30]. Condensation of 5-HMF is assumed to be responsible for humins formation in the acid-catalyzed carbohydrate conversion [31].…”

Section: Resultsmentioning

confidence: 99%

The Nature and Mechanism of Selectivity Decrease of the Acid-catalyzed Fructose Conversion with Increasing the Carbohydrate Concentration

Chernyak¹,

Tarabanko²,

Смирнова³

et al. 2015

J. Sib. Fed. Univ. Chem.

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Formation and Growth of Humins via Aldol Addition and Condensation during Acid-Catalyzed Conversion of 5-Hydroxymethylfurfural

Cited by 491 publications

References 39 publications

Comprehensive Understanding of the Role of Brønsted and Lewis Acid Sites in Glucose Conversion into 5‐Hydromethylfurfural

Comprehensive Understanding of the Role of Brønsted and Lewis Acid Sites in Glucose Conversion into 5‐Hydromethylfurfural

Tailoring the porosity of chemically activated hydrothermal carbons: Influence of the precursor and hydrothermal carbonization temperature

The Nature and Mechanism of Selectivity Decrease of the Acid-catalyzed Fructose Conversion with Increasing the Carbohydrate Concentration

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