The production of fructose from carbohydrate feedstocks

A review of the general chromatographic theory and of continuous chromatographic techniques has been carried out. Three methods of inversion of sucrose to glucose and fructose in beet molasses were explored. These methods were the inversion of sucrose using the enzyme invertase, by the use of hydrochloric acid and the use of the resin Amberlite IR118 in the H+ form. The preferred method on economic and purity considerations was by the use of the enzyme invertase. The continuous chromatographic separation of inverted beet molasses resulting in a fructose rich product and a product containing glucose and other non-sugars was carried out using a semi-continuous counter-current chromatographic refiner (SCCR6), consisting of ten 10.8cm x 75cm long stainless steel columns packed with a calcium charged 8% cross-linked polystyrene resin Zerolit SRC 14. Based on the literature this is the first time such a continuous separation has been attempted. It was found that the cations present in beet molasses displaced the calcium ions from the resin resulting in poor separation of the glucose and fructose. Three methods of maintaining the calcium form of the resin during the continuous operation of the equipment were established. Passing a solution of calcium nitrate through the purge column for half a switch period was found to be most effective as there was no contamination of the main fructose rich product and the product concentrations were increased by 50%. When a 53% total solids (53 Brix) molasses feedstock was used, the throughput was 34.13kg sugar solids per m3 of resin per hour. Product purities of 97% fructose in fructose rich (FRP) and 96% glucose in the glucose rich (GRP) products were obtained with product concentrations of 10.93 %w/w for the FRP and 10.07 %w/w for the GRP. The effects of flowrates, temperature and background sugar concentration on the distribution coefficients of fructose, glucose, betaine and an ionic component of beet molasses were evaluated and general relationships derived. The computer simulation of inverted beet molasses separations on an SCCR system has been carried out successfully.

Rational design of heterogeneous catalysts for biodiesel synthesis

Dwindling oil reserves and growing concerns over carbon dioxide emissions and associated climate change are driving the utilisation of renewable feedstocks as alternative, sustainable fuel sources. Catalysis has a rich history of facilitating energy efficient, selective molecular transformations, and contributes to 90% of current chemical manufacturing processes. In a post-petroleum era, catalysis will be pivotal in overcoming the scientific and engineering barriers to economically feasible bio-fuels. This perspective highlights some recent developments in heterogeneous catalysts for the synthesis of biodiesel from renewable resources, derived from plant and aquatic oil sources. Particular attention will be paid to the importance of catalyst pore architecture, surface polarity and acid and base properties, in meeting the challenge of transforming highly polar and viscous bio-based reactants. © 2012 The Royal Society of Chemistry.

Tuning solid acid catalysts for glucose conversion to platform chemicals

Worldwide concern over dwindling fossil fuel reserves and impact of CO2 emissions on climate change means there is an urgent need to reduce our dependence on oil based sources of fuels and chemicals. The direct conversion of lignocellulosic derived glucose to 5-Hydroxymethylfurfural (5-HMF) is an attractive process for the production of chemicals and fuels but requires a bi-functional catalyst with acid-base or Lewis-Brönsted sites which can operate efficiently in the aqueous phase. While conventionally viewed as a superacid, the potential for tuning the acid strength in SO4/ZrO2 and potential for coupling bi-functional ZrO2-SO4/ZrO2 sites at low sulfate contents have been overlooked. Our previous work has shown effective tuning of the acid strength in SO4/ZrO2 can be used to direct selectivity in terpene isomerisation thus we rationalised control over HMF selectivity could achieved in a similar fashion. Here we report on a systematic study of the impact of acid properties of SO4/ZrO2 catalysts on the conversion of C6 sugars to 5-HMF in aqueous media and correlate the surface acid-base properties with glucose isomerisation and dehydration capabilities.

Heterogeneous catalysts for converting renewable feedstocks to fuels and chemicals

The combination of dwindling oil reserves and growing concerns over carbon dioxide emissions and associated climate change is driving the urgent development of routes to utilise renewable feedstocks as sustainable sources of fuel and chemicals. Catalysis has a rich history of facilitating energy-efficient selective molecular transformations and contributes to 90% of chemical manufacturing processes and to more than 20% of all industrial products. In a post-petroleum era, catalysis will be central to overcoming the engineering and scientific barriers to economically feasible routes to biofuels and chemicals. This chapter will highlight some of the recent developments in heterogeneous catalytic technology for the synthesis of fuels and chemicals from renewable resources, derived from plant and aquatic oil sources as well as lignocellulosic feedstocks. Particular attention will be paid to the challenges faced when developing new catalysts and importance of considering the design of pore architectures and effect of tuning surface polarity to improve catalyst compatibility with highly polar bio-based substrates.

Carbon nanotube-supported metal catalysts for NOx reduction using hydrocarbon reductants. Part 1:catalyst preparation, characterization and NOx reduction characteristics

A dual catalyst system for the Selective Catalytic Reduction of NOx with hydrocarbons (HC-SCR), including distinct low and high temperature formulations, is proposed as a means to abate NOx emissions from diesel engines. Given that satisfactory high temperature HC-SCR catalysts are already available, this work focuses on the development of an improved low temperature formulation. Pt supported on multiwalled carbon nantubes (MWCNTs) was found to exhibit superior NOx reduction activity in comparison with Pt/Al2O3, while the MWCNT support displayed a higher resistance to oxidation than activated carbon. Refluxing the MWCNT support in a 1:1 mixture of H2SO4 and HNO3 prior to the metal deposition step proved to be beneficial for the metal dispersion and the NOx reduction performance of the resulting catalysts. This support effect is ascribed to the increased Brønsted acidity of the acid-treated MWCNTs, which in turn enhances the partial oxidation of the hydrocarbon reductant. Further improvements in the HC-SCR performance of MWCNT-based formulations were achieved using a 3:1 Pt–Rh alloy as the supported phase.

Designer catalysts for biodiesel synthesis

The combination of dwindling oil reserves and growing concerns over carbon dioxide emissions and associated climate change is driving the urgent development of clean, sustainable energy supplies. Biodiesel is a non-toxic and biodegradable fuel, with the potential for closed CO2 cycles and thus vastly reduced carbon footprints compared with petroleum. However, current manufacturing routes employing soluble catalysts are very energy inefficient, with their removal necessitating an energy intensive separation to purify biodiesel, which in turn produces copious amounts of contaminated aqueous waste. The introduction of non-food based feedstocks and technical advances in heterogeneous catalyst and reactor design are required to ensure that biodiesel remains a key player in the renewable energy sector for the 21st century. Here we report on the development of tuneable solid acid and bases for biodiesel synthesis, which offer several process advantages by eliminating the quenching step and allowing operation in a continuous reactor. Significant progress has been made towards developing tuneable solid base catalysts for biodiesel synthesis, including Li/CaO [1], Mg-Al hydrotalcites [2] and calcined dolomite [3] which exhibit excellent activity for triglyceride transesterification. However, the effects of solid base strength on catalytic activity in biodiesel synthesis remains poorly understood, hampering material optimisation and commercial exploitation. To improve our understanding of factors influencing solid base catalysts for biodiesel synthesis, we have applied a simple spectroscopic method for the quantitative determination of surface basicity which is independent of adsorption probes. Such measurements reveal how the morphology and basicity of MgO nanocrystals correlate with their biodiesel synthesis activity [4]. While diverse solid acids and bases have been investigated for TAG transesterification, the micro and mesoporous nature of catalyst systems investigated to date are not optimal for the diffusion of bulky and viscous C16-C18 TAGs typical of plant oils. The final part of this presentation will address the benefits of designing porous networks comprising interconnected hierarchical macroporous and mesoporous channels (Figure 1) to enhance mass-transport properties of viscous plant oils during biodiesel synthesis [5]. References: [1] R.S. Watkins, A.F. Lee, K. Wilson, Green Chem., 2004, 6, 335. [2]D.G. Cantrell, L.J. Gillie, A.F. Lee and K. Wilson, Appl. Catal. A, 2005, 287,183. [3] C. Hardacre, A.F. Lee, J.M. Montero, L. Shellard, K.Wilson, Green Chem., 2008, 10, 654. [4] J.M. Montero, P.L. Gai, K. Wilson, A.F. Lee, Green Chem., 2009, 11, 265. [5] J. Dhainaut, J.-P. Dacquin, A.F. Lee, K. Wilson, Green Chem., 2010, 12, 296.

Catalytic systems based on carbon fiber materials for the low-temperature oxidation of carbon monoxide

New heterogenized catalytic systems for the low-temperature oxidation of CO were synthesized by supporting solutions of Pd, Cu, and Fe salts on carbon fibrous materials (carbopon and busofit). The carbon supports were studied by elemental analysis, SEM, TGA, and TPD. The effects of the nature of the support, the concentration and composition of the active component, and the conditions of preparation on the efficiency of the catalytic system were studied. It was ascertained that attenuation of hydrophilic properties of the support led to the decrease in system activity. The investigation of the catalysts by XPS showed that sample treatment in the reaction medium results in redistribution of the components of the active phase in the near-surface layer of the catalyst. The catalytic system based on carbon fibrous material carbopon prepared by supporting active components (Pd, Cu, and Fe salts) in three stages with intermediate activation in the reaction medium ensures 95% conversion of CO under respiratory conditions, and is promising for the design of the main element of breathing masks on its basis.

Simulation process of biodiesel production over heterogeneous catalysts

Biodiesel production is a very promising area due to the relevance that it is an environmental-friendly diesel fuel alternative to fossil fuel derived diesel fuels. Nowadays, most industrial applications of biodiesel production are performed by the transesterification of renewable biological sources based on homogeneous acid catalysts, which requires downstream neutralization and separation leading to a series of technical and environmental problems. However, heterogeneous catalyst can solve these issues, and be used as a better alternative for biodiesel production. Thus, a heuristic diffusion-reaction kinetic model has been established to simulate the transesterification of alkyl ester with methanol over a series of heterogeneous Cs-doped heteropolyacid catalysts. The novelty of this framework lies in detailed modeling of surface reacting kinetic phenomena and integrating that with particle-level transport phenomena all the way through to process design and optimisation, which has been done for biodiesel production process for the first time. This multi-disciplinary research combining chemistry, chemical engineering and process integration offers better insights into catalyst design and process intensification for the industrial application of Cs-doped heteropolyacid catalysts for biodiesel production. A case study of the transesterification of tributyrin with methanol has been demonstrated to establish the effectiveness of this methodology.

Simulation process of biodiesel production over heterogeneous catalysts

Biodiesel production is a very promising area due to the relevance that it is an environmental-friendly diesel fuel alternative to fossil fuel derived diesel fuels. Nowadays, most industrial applications of biodiesel production are performed by the transesterification of renewable biological sources based on homogeneous acid catalysts, which requires downstream neutralization and separation leading to a series of technical and environmental problems. However, heterogeneous catalyst can solve these issues, and be used as a better alternative for biodiesel production. Thus, a heuristic diffusion-reaction kinetic model has been established to simulate the transesterification of alkyl ester with methanol over a series of heterogeneous Cs-doped heteropolyacid catalysts. The novelty of this framework lies in detailed modeling of surface reacting kinetic phenomena and integrating that with particle-level transport phenomena all the way through to process design and optimisation, which has been done for biodiesel production process for the first time. This multi-disciplinary research combining chemistry, chemical engineering and process integration offers better insights into catalyst design and process intensification for the industrial application of Cs-doped heteropolyacid catalysts for biodiesel production. A case study of the transesterification of tributyrin with methanol has been demonstrated to establish the effectiveness of this methodology.

New insights in the deactivation of sulfonic modified SBA-15 catalysts for biodiesel production from low-grade oleaginous feedstock

Arenesulfonic-acid functionalized SBA-15 materials have been used in the production of biodiesel from low grade oleaginous feedstock. These materials display an outstanding catalytic activity, being able to promote the transformation of crude palm oil with methanol into fatty acid methyl esters with high yield (85%) under mild reaction conditions. However, high sensitivity of the catalyst against poisoning by different substances has also been detected. Thus, alkaline metal cations, such as sodium or potassium exert a negative influence on the catalytic activity of these materials, being necessary amounts around 500 ppm of sodium in the reaction media to decrease the catalytic activity of these materials to a half of its initial value in just two reaction runs. The deactivation of arenesulfonic acid functionalized SBA-15 materials seems to occur in this case by ion exchange of the acid protons at the sulfonic groups. Organic unsaponifiable compounds like lecithin or retinol also induce a negative influence in the catalytic activity of these sulfonic acid-based materials, though not so intense as in the case of alkaline metals. The deactivating mechanism associated to the influence of the organic compounds seems to be linked to the adsorption of such substances onto the catalytic acid sites as well as on the silica surface. The accumulation of lecithin in the surface of catalyst, observed by means of thermogravimetric analysis, suggest the creation of a strong interaction, probably by ion pair, between this compound and the sulfonic acid group.

A simple and efficient procedure for Knoevenagel reaction promoted by imidazolium-based ionic liquids

Various room temperature ionic liquids (RTILs), notably, 1-methoxyethyl-3-methylimidazolium trifluoroacetate [MeOEtMIM]+[CF3COO]ˉ , have been used to promote the Knoevenagel condensation to afford substituted olefins. All reactions proceeded effectively in the absence of any other catalysts or co-solvents with good to excellent yields. This method is simple and applicable to reactions involving a wide range of aldehydes and ketones with methylene compounds. The ionic liquid can be recycled without noticeable reduction of its catalytic activity. A plausible reaction mechanism is proposed.

Preparation of Polymer Nanoparticles by Ring Opening Metathesis Polymerization in Aqueous Dispersed Systems with Water-Soluble Ruthenium-based Catalyst

Ring opening metathesis polymerization (ROMP) is a variant of olefin metathesis used to polymerize strained cyclic olefins. Ruthenium-based Grubbs’ catalysts are widely used in ROMP to produce industrially important products. While highly efficient in organic solvents such as dichloromethane and toluene, these hydrophobic catalysts are not typically applied in aqueous systems. With the advancements in emulsion and miniemulsion polymerization, it is promising to conduct ROMP in an aqueous dispersed phase to generate well-defined latex nanoparticles while improving heat transfer and reducing the use of volatile organic solvents (VOCs). Herein I report the efforts made using a PEGylated ruthenium alkylidene as the catalyst to initiate ROMP in an oil-in-water miniemulsion. 1H NMR revealed that the synthesized PEGylated catalyst was stable and reactive in water. Using 1,5-cyclooctadiene (COD) as monomer, we showed the highly efficient catalyst yielded colloidally stable polymer latexes with ~ 100% conversion at room temperature. Kinetic studies demonstrated first-order kinetics with good livingness as confirmed by the shift of gel permeation chromatography (GPC) traces. Depending on the surfactants used, the particle sizes ranged from 100 to 300 nm with monomodal distributions. The more strained cyclic olefin norbornene (NB) could also be efficiently polymerized with a PEGylated ruthenium alkylidene in miniemulsion to full conversion and with minimal coagulum formation.

Copper-cobalt foams as active and stable catalysts for hydrogen release by hydrolysis of sodium borohydride

The progress of hydrogen generation by sodium borohydride hydrolysis depends highly on the development of efficient catalysts based on non-noble metals such as cobalt. However, such catalysts undergo extensive deactivation which has a detrimental effect on their stability. Herein, highly porous copper and cobalt-based bimetallic foams, CuxCo100-x (x = 0-100 at%), produced by electrodeposition using the dynamic hydrogen bubble template are reported. The chemical composition of the foams was optimized in order to enhance specific surface area and improve their catalytic activity and stability as heterogeneous catalysts for sodium borohydride hydrolysis. Among the tested catalysts, copper-rich samples like Cu85Co15 are slightly more active than Co-100 and above all, they are less sensitive to deactivation by borates adsorption. Porous copper-rich foams were found to be an alternative to cobalt as low-cost, active and stable heterogeneous catalysts for hydrogen generation by hydrolysis of sodium borohydride. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

New biomass derived carbon catalysts for biomass valorization

Due to diminishing petroleum reserves, unsteady market situation and the environmental concerns associated with utilization of fossil resources, the utilization of renewables for production of energy and chemicals (biorefining) has gained considerable attention. Biomass is the only sustainable source of organic compounds that has been proposed as petroleum equivalent for the production of fuels, chemicals and materials. In fact, it would not be wrong to say that the only viable answer to sustainably convene our future energy and material requirements remain with a bio-based economy with biomass based industries and products. This has prompted biomass valorization (biorefining) to become an important area of industrial research. While many disciplines of science are involved in the realization of this effort, catalysis and knowledge of chemical technology are considered to be particularly important to eventually render this dream to come true. Traditionally, the catalyst research for biomass conversion has been focused primarily on commercially available catalysts like zeolites, silica and various metals (Pt, Pd, Au, Ni) supported on zeolites, silica etc. Nevertheless, the main drawbacks of these catalysts are coupled with high material cost, low activity, limited reusability etc. – all facts that render them less attractive in industrial scale applications (poor activity for the price). Thus, there is a particular need to develop active, robust and cost efficient catalytic systems capable of converting complex biomass molecules. Saccharification, esterification, transesterification and acetylation are important chemical processes in the valorization chain of biomasses (and several biomass components) for production of platform chemicals, transportation fuels, food additives and materials. In the current work, various novel acidic carbons were synthesized from wastes generated from biodiesel and allied industries, and employed as catalysts in the aforementioned reactions. The structure and surface properties of the novel materials were investigated by XRD, XPS, elemental analysis, SEM, TEM, TPD and N2-physisorption techniques. The agro-industrial waste derived sulfonic acid functionalized novel carbons exhibit excellent catalytic activity in the aforementioned reactions and easily outperformed liquid H2SO4 and conventional solid acids (zeolites, ion-exchange resins etc). The experimental results indicated strong influence of catalyst pore-structure (pore size, pore-volume), concentration of –SO3H groups and surface properties in terms of the activity and selectivity of these catalysts. Here, a large pore catalyst with high –SO3H density exhibited the highest esterification and transesterification activity, and was successfully employed in biodiesel production from fatty acids and low grade acidic oils. Also, a catalyst decay model was proposed upon biodiesel production and could explain that the catalyst loses its activity mainly due to active site blocking by adsorption of impurities and by-products. The large pore sulfonated catalyst also exhibited good catalytic performance in the selective synthesis of triacetin via acetylation of glycerol with acetic anhydride and out-performed the best zeolite H-Y with respect to reusability. It also demonstrated equally good activity in acetylation of cellulose to soluble cellulose acetates, with the possibility to control cellulose acetate yield and quality (degree of substitution, DS) by a simple adjustment of reaction time and acetic anhydride concentration. In contrast, the small pore and highly functionalized catalysts obtained by hydrothermal method and from protein rich waste (Jatropha de-oiled waste cake, DOWC), were active and selective in the esterification of glycerol with fatty acids to monoglycerides and saccharification of cellulosic materials, respectively. The operational stability and reusability of the catalyst was found to depend on the stability of –SO3H function (leaching) as well as active site blocking due to adsorption of impurities during the reaction. Thus, our results corroborate the potential of DOWC derived sulfated mesoporous active carbons as efficient integrated solid acid catalysts for valorization of biomass to platform chemicals, biofuel, bio-additive, surfactants and celluloseesters.