Kinetic study of the decomposition of 2‐butanol on carbon‐based acid catalyst

The catalytic conversion of 2‐butanol on a carbon‐based acid catalyst prepared by chemical activation of olive stone with phosphoric acid was investigated. The carbon catalyst showed a considerable amount of surface phosphorus, presumably in form of phosphate groups, as revealed by XPS, despite a washing step carried out after the activation process. Conversion of 2‐butanol yields mainly dehydration products, mostly cis‐2‐butene and trans‐2‐butene with lower amounts of 1‐butene, and a very small amount of mek as dehydrogenation product. Kinetic interpretation of the experimental data was performed using two elimination mechanisms for the dehydration reaction; an E1‐mechanism (two‐step mechanism) and an E2‐mechanism (one‐step mechanism). The rate expressions derived from both models fit properly the experimental results, suggesting that probably the two mechanisms occur simultaneously. This is supported by the similar rate constant obtained for the formation of the carbocation and the olefins in the E1 and E2 mechanisms, respectively. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

The Heterogeneity of Glass Surfaces Revealed by Temperature Programmed Desorption

Adsorption of butanol and pyridine on E‐glass fibers with three different compositions, as well as on powders of silica and the crushed fibers, was studied by temperature programmed desorption (TPD) with a mass‐sensitive detector. In the case of butanol, there are two types of desorbing molecules: at lower temperatures butanol desorbs, but in the range 450°C–600°C, 1‐butene desorption is also observed. It is shown that 1‐butene desorption is due to thermal decomposition of butanol chemisorbed to OH groups on both the glass and silica surfaces. The binding energy distributions of adsorption sites for butanol and pyridine are similar on all three glass compositions, but they are much more heterogeneous compared to silica; this difference is most evident for pyridine and is attributed to the presence Al and B in the glasses. The decomposition temperature of chemisorbed butanol is highest for silica and depends on glass composition for the fibers and powders. Interestingly, the glass which does not contain boron shows a well‐defined peak for the decomposition of chemisorbed butanol, suggestive of unique adsorption sites on this boron‐free surface; but they are much less temperature stable than the chemisorption sites on silica. In situ exposure to water vapor increased the number of active sites for chemisorption.     

Improvement of mono and diacylglycerol production via enzymatic glycerolysis in tert‐butanol system

In this work we report experimental data regarding the glycerolysis of olive oil using Novozym 435 in tert‐butanol organic system aiming at the production of monoacylglycerols (MAG) and diacylglycerols (DAG). Experiments were performed in batch mode, recording the reaction kinetics and evaluating the effects of temperature, enzyme concentration, tert‐butanol:oil/glycerol volume ratio and using solvent to substrates ratio of 1:1 and 5:1 v/v. Experimental results showed that lipase‐catalyzed glycerolysis in tert‐butanol might be a potential route for the production of high contents of MAG and DAG. The results also showed that it is possible to maximize the production of MAG and/or DAG, depending on the glycerol to oil molar ratio employed in the reactional system. Higher contents of MAG (53 wt%) and DAG (50 wt%) were achieved using glycerol to oil molar ratio of 3:1/6:1 and 0.5:1.5, respectively, both in 8 h of reaction at 70°C, 600 rpm and enzyme concentration of 10 wt%.     

Separation of a Biofuel: Recovery of Biobutanol by Salting‐Out and Distillation

The second generation biofuel butanol can be produced by acetone‐butanol‐ethanol (ABE) fermentation, but the separation from the broth is still challenging. Therefore, dipotassium hydrogen phosphate was investigated as salting‐out agent. The ABE fermentation broth was enriched by a prefractionator after being preheated. The enriched ABE solution was salted out by K₂HPO₄ solutions at different temperatures. The water in the supplemented ABE solution was largely removed by the salting‐out method. The energy requirements for the prefractionator and the butanol column were significantly reduced. The total energy demand for the recovery of acetone, butanol, and ethanol by salting‐out and subsequent distillation was optimized. With the salting‐out process, the entire salting‐out and distillation method turned out to be more energy‐saving than the conventional one.     

新型固体酸催化丁醇和环氧乙烷醚化

研究了丁醇和环氧乙烷在一种新型固体酸催化剂上的醚化反应。结果表明,这种新型固体酸具有很高的催化活性和较窄的相对分子质量分布。采用间歇釜式外循环反应器,在n丁醇∶n环氧乙烷=4∶1(物质的量比)、催化剂的质量为丁醇质量的0.4%、反应温度120℃、操作压力0.2~0.3 MPa的条件下,环氧乙烷的转化率为100%、乙二醇单丁醚的选择性较好。确定了最佳工艺参数并成功地进行了工业放大。     

Hydrogen production via dry reforming of butanol: Thermodynamic analysis

Dry reforming of butanol for hydrogen production has been studied by Gibbs free energy minimization method. The calculation results showed that the formation of hydrogen and carbon monoxide was through a multi-step pathway via the dehydrogenation, dehydration, decomposition and carbon dioxide reforming of butanol. The optimum conditions for hydrogen production are identified: reaction temperatures between 1150 and 1200 K and carbon dioxide-to-butanol molar ratios between 3.5 and 4.0 at 1 atm. Under the above conditions, 100% conversion of butanol, 34.91-37.98% concentration of hydrogen and 57.34−57.87% concentration of carbon monoxide could be achieved in the absence of coke formation. The butanol dry reforming with carbon dioxide is suitable for providing fuels for Solid Oxide Fuel Cell (SOFC). The coke-formed and coke-free regions are found, which are useful in guiding the search for suitable catalysts for the reaction.     

Oxidative dehydrogenation of butenes over Bi‐Mo and Mo‐V based catalysts in a two‐zone fluidized bed reactor

The oxidative dehydrogenation of a 1‐butene/trans‐butene (1:1) mixture to 1,3‐butadiene was carried out in a two‐zone fluidized bed reactor using a Mo‐V‐MgO and a γ‐Bi₂MoO₆ catalyst. The significant operating conditions temperature, oxygen/butene molar ratio, butene inlet height, and flow velocity were varied to gain high 1,3‐butadiene selectivity and yield. Furthermore, axial concentration profiles were measured inside the fluidized bed to gain insight into the reaction network in the two zones. For optimized conditions and with a suitable catalyst, the two‐zone fluidized bed reactor makes catalyst regeneration and catalytic reaction possible in a single vessel. In the lower part of the fluidized bed, the oxidation of coke deposits on the catalyst as well as the filling of oxygen vacancies in the lattice can occur. The oxidative dehydrogenation reaction takes place in the upper zone. Thorough particle mixing inside fluidized beds causes permanent particle exchange between both zones. © 2016 American Institute of Chemical Engineers AIChE J, 63: 43–50, 2017     

Application of lipase immobilized on nylon‐6 for the synthesis of butyl acetate by transesterification reaction in n‐heptane

A purified alkaline thermotolerant bacterial lipase from Bacillus coagulans BTS‐3 was immobilized on nylon‐6 matrix activated by glutaraldehyde. The matrix showed ～ 70% binding efficiency for lipase. The bound lipase was used to perform transesterification in n‐heptane. The reaction studied was conversion of vinyl acetate and butanol to butyl acetate and vinyl alcohol. Synthesis of butyl acetate was used as a parameter to study the transesterification reaction. The immobilized enzyme achieved ～ 75% conversion of vinyl acetate and butanol (100 mmol/L each) into butyl acetate in n‐heptane at 55°C in 12 h. When alkane of C‐chain lower or higher than n‐heptane was used as an organic solvent, the conversion of vinyl acetate and butanol to butyl acetate decreased. During the repetitive transesterification under optimal conditions, the nylon bound lipase produced 77.6 mmol/L of butyl acetate after third cycle of reuse. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Study on the Synthesis of n‐Butyl Acetate by Catalytic Rectification

With Hβ zeolite as the catalyst and θ rings as the fillings, the technological process of synthesizing n‐butyl acetate with acetic acid and n‐butanol in a Φ 30 mm and 2 m tall catalytic rectifying column was studied. The influence of factors such as catalyst loading height, material feed site, reflux ratio and feed rate on the esterification reaction and the rectification effect was investigated. The study results suggested that the appropriate conditions of n‐butyl acetate synthesis by catalytic rectification include: The height ratio of the rectifying section, the reaction section and the stripping section is 1:1:1; acetic acid and n‐butanol are fed in upside and downside of the reaction section, respectively; the reflux ratio is 2.5; the liquid hourly space velocity of n‐butanol is 0.64 h^–1. Under these conditions, the mass fraction of n‐butyl acetate in the column bottom is 98.64 %, and the total yield of n‐butyl acetate is 91.5 %.     

Reaction Kinetics of Steam Reforming of n‐Butanol over a Ni/Hydrotalcite Catalyst

Pyrolytic lignin can be transformed to liquid transportation fuels by hydrotreatment, which requires hydrogen (H₂). Bio‐oil is a suitable renewable feedstock for H₂ production. Here, n‐butanol was chosen as a model compound representing alcohols in the bio‐oil aqueous fraction. H₂ production from steam reforming of n‐butanol was investigated in a fixed‐bed reactor using a commercial Ni/hydrotalcite catalyst. A plausible reaction pathway in the presence of Ni was discussed. An increase in reforming temperature, space time, and steam/carbon ratio in the feed enhanced the n‐butanol conversion and H₂ yield. Reaction kinetics was studied in the defined chemical control regime. The reaction order with respect to n‐butanol (one) and the activation energy were determined.     

Butanol production in a sugarcane biorefinery using ethanol as feedstock. Part II: Integration to a second generation sugarcane distillery

Production of second generation ethanol and other added value chemicals from sugarcane bagasse and straw integrated to first generation sugarcane biorefineries presents large potential for industrial implementation, since part of the infrastructure where first generation ethanol is produced may be shared between both plants. In this context, butanol from renewable resources has attracted increasing interest, mostly for its use as a drop in liquid biofuel for transportation, since its energy density is greater than that of ethanol, but also for its use as feedstock in the chemical industry. In this paper, vapor-phase catalytic production of butanol from first and second generation ethanol in a sugarcane biorefinery was assessed, using data available from the literature. The objective is to evaluate the potential of butanol either as fuel or feedstock for industry, taking into account economical/environmental issues through computer simulation. The results obtained show that, although promising, butanol sold as chemical has a limited market and as fuel presents economic constraints. In addition, investments on the butanol conversion plant could be an obstacle to its practical implementation. Nevertheless, environmental assessment pointed out advantages of its use as fuel for road transportation, if compared with gasoline in terms of global environmental impacts such as global warming.     

Exploring the potential of recovering 1‐butanol from aqueous solutions by liquid demixing upon addition of carbohydrates or salts

BACKGROUND: Fermentative production of 1‐butanol yields dilute aqueous solutions. Recovery of the butanol from these solutions is most commonly performed by energy‐intensive distillation. This work investigated the liquid‐liquid (L‐L) phase behavior of mixtures of butanol and water to explore the potential of using L‐L phase separation as a recovery possibility for 1‐butanol. The phase behavior is preferably influenced by compounds already present in the fermentation, such as carbohydrates and salts. RESULTS: The L‐L phase equilibria of butanol and water were determined in the presence of glucose, fructose, sucrose, NaCl, LiCl and CaCl₂. The aqueous and organic phase split is more pronounced in the presence of salts than in the presence of carbohydrates. Demixing is achieved with about 0.3 kg salt kg^?1 aqueous phase containing 40 g of butanol. CONCLUSION: Operation of L‐L based recovery using salts or carbohydrates requires extreme concentrations of those compounds. For feed material containing 40 g kg^?1 butanol, the tested carbohydrates do not influence the phase equilibria sufficiently to allow butanol separation. Fermentative butanol concentrations up to 70 g kg^?1 are required to create an effective L‐L phase split. The remaining residual aqueous carbohydrate solution might be used as feed for a following fermentation. Copyright © 2011 Society of Chemical Industry     

Selective separation of n‐butanol from aqueous solutions by pervaporation using silicone rubber‐coated silicalite membranes

BACKGROUND: To use butanol as a liquid fuel and feedstock, it is necessary to establish processes for refining low‐concentration butanol solutions. Pervaporation (PV) employing hydrophobic silicalite membranes for selective recovery of butanol is a promising approach. In this study, the adsorption behavior of components present in clostridia fermentation broths on membrane material (silicalite powder) was investigated. The potential of PV using silicone rubber‐coated silicalite membranes for the selective separation of butanol from model acetone–butanol–ethanol (ABE) solutions was investigated. RESULTS: The equilibrium adsorbed amounts of ABE per gram of silicalite from aqueous solutions of binary mixtures at 30 °C increased as follows: ethanol (95 mg) < acetone (100 mg) < n‐butanol (120 mg). The amount of butanol adsorbed is decreased by the adsorption of acetone and butyric acid. In the separation of ternary butanol/water/acetone mixtures, the enrichment factor for acetone decreased, compared with that in binary acetone/water mixtures. In the separation of a model acetone–butanol–ethanol (ABE) fermentation broth containing butyric acid by PV using a silicone rubber‐coated silicalite membrane, the permeate butanol concentration was comparable with that obtained in the separation of a model ABE broth without butyric acid. The total flux decreased with decreasing feed solution pH. CONCLUSION: A silicone rubber‐coated silicalite membrane exhibited highly selective PV performance in the separation of a model ABE solution. It is very important to demonstrate the effectiveness of PV in the separation of actual clostridia fermentation broths, and to identify the factors affecting PV performance. Copyright © 2011 Society of Chemical Industry     

Butanol production in a sugarcane biorefinery using ethanol as feedstock. Part I: Integration to a first generation sugarcane distillery

Butanol production from renewable resources has been increasingly investigated over the past decade, mostly for its use as a liquid biofuel for road transportation, since its energy density is higher than that of ethanol and it may be used in gasoline driven engines with practically no changes, but also for use as a feedstock in the chemical industry. Most of the research concerning butanol production focuses on the ABE process (fermentation of sugars into a mixture of acetone, butanol and ethanol), which has several drawbacks regarding microorganism performance and product inhibition. An alternative to ABE fermentation, ethanol catalytic conversion to butanol can produce a higher quality product with less retrofitting than ABE in existing ethanol producing facilities. There are different types of catalysts for the chemical conversion of ethanol to butanol being developed in laboratory scale, but their actual use in a sugarcane processing plant has never before been assessed. Butanol production from ethanol in a sugarcane biorefinery, using data from the literature, was assessed in this study; different technological alternatives (catalytic routes) were evaluated through computer simulation in Aspen Plus (including production of electricity, sugar, ethanol and other products) and economic and environmental impacts were assessed. Results indicate that vapor-phase catalysis presents higher potential for industrial implementation, and commercialization of butanol for use as a chemical feedstock has an economic performance similar to that of current, optimized first generation sugarcane distilleries, but can potentially contribute to cost reduction that will allow commercialization of butanol as a fuel in the future.     

Kinetic study of 1‐butanol dehydration to di‐n‐butyl ether over Amberlyst 70

Kinetics of the catalytic dehydration of 1‐butanol to di‐n‐butyl ether (DNBE) over Amberlyst 70 was investigated. Experiments were performed in liquid phase at 4 MPa and 413–463 K. Three elementary reaction mechanisms were considered: a Langmuir–Hinselwood–Hougen–Watson (LHHW) formulation; an Eley–Rideal (ER) formulation in which DNBE remains adsorbed; an ER formulation in which water remains adsorbed. Two kinetic models explain satisfactorily the dehydration of 1‐butanol to DNBE: a LHHW formalism in which the surface reaction between two adjacent adsorbed molecules of 1‐butanol is the rate limiting step (RLS) and where the adsorption of water is negligible, and a mechanism in which the RLS is the desorption of water being the adsorption of DNBE negligible. In both models, the strong inhibiting effect of water was successfully taken into account by means of a correction factor derived from a Freundlich adsorption isotherm. Both models present similar values of apparent activation energies (122 ± 2 kJ/mol). © 2015 American Institute of Chemical Engineers AIChE J, 62: 180–194, 2016     

Characteristics of diether‐ and phthalate‐based Ziegler‐Natta catalysts for copolymerization of propylene and ethylene and terpolymerization of propylene,ethylene, and 1‐butene

Copolymerization of propylene and ethylene and terpolymerization of propylene, ethylene, and 1‐butene were carried out to compare the characteristics of diether‐ and phthalate‐based Ziegler‐Natta catalysts in a reaction system of pilot scale. The ethylene incorporation with the diether‐based catalyst was higher but the 1‐butene incorporation was lower compared with those of the phthalate‐based catalyst. In the case of copolymers from the diether‐based catalyst, melting behavior, determined through differential scanning calorimetry (DSC), showed a distinct shoulder peak and lots of nuclei were formed during crystallization. The diether‐based catalyst led to polymers having blockier ethylene sequences compared with those of the phthalate‐based catalyst; the highly crystallizable fraction (HIS) containing blockier ethylene sequences was produced with the diether‐based catalyst. These results seem to be the result of regio‐irregular characteristics of the diether‐based catalyst. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 851‐859, 2013     

Fabrication of graphene oxide composite membranes and their application for pervaporation dehydration of butanol

As a new kind of 2D nanomaterials, graphene oxide (GO) with 2–4 layers was fabricated via a modified Hummers method and used for the preparation of pervaporation (PV) membranes. Such GO membranes were prepared via a facile vacuum-assisted method on anodic aluminium oxide disks and applied for the dehydration of butanol. To obtain GO membranes with high performance, effects of pre-treatments, including high-speed centrifugal treat-ment of GO dispersion and thermal treatment of GO membranes, were investigated. In addition, effects of oper-ation conditions on the performance of GO membranes in the PV process and the stability of GO membranes were also studied. It is of benefit to improve the selectivity of GO membrane by pre-treatment that centrifuges the GO dispersion with 10000 r·min?1 for 40 min, which could purify the GO dispersion by removing the large size GO sheets. As prepared GO membrane showed high separation performance for the butanol/water system. The separation factor was 230, and the permeability was as high as 3.1 kg·m?2·h?1 when the PV temperature was 50 °C and the water content in feed was 10%(by mass). Meanwhile, the membrane still showed good stabil-ity for the dehydration of butanol after running for 1800 min in the PV process. GO membranes are suitable candidates for butanol dehydration via PV process.     

Epoxidation of a Series of C2–C6 Olefins in the Gas Phase

Epoxidation of ethylene, propylene, 2‐methylpropene, trans‐2‐butene, 2‐methyl‐2‐butene, and 2,3‐dimethyl‐2‐butene were carried out in a flow‐through reactor in the homogeneous gas phase at pressures of 0.25–1.0 bar in the temperature range of 250–375 °C. Residence times in the reactor varied from 8.3 to 38 ms. The oxidizing agent needed in the feed gas is ozone. The O₃ efficiency (reacted olefin/initial O₃) was found to be strongly dependent on the reactivity of the olefin used. For C₄–C₆ olefins, the O₃ efficiency was better than 75 % in each case. For 2‐methyl‐2‐butene and 2,3‐dimethyl‐2‐butene, the O₃ efficiency exceeded the theoretical value of 100 % considerably. The selectivity to epoxide was about 90 % independent of the olefin used. Under conditions of nearly total olefin conversion, the high selectivity to the epoxide has been retained as unchanged. There were no indications for consecutive reactions of the epoxides.     

Oxidative Dehydrogenation of a C4 Raffinate‐2 towards 1,3‐Butadiene in a Two‐Zone Fluidized Bed

The oxidative dehydrogenation of a C4 raffinate‐2 consisting of n‐butane, 1‐butene, and 2‐butene was conducted in a two‐zone fluidized bed reactor using a Mo‐V‐MgO catalyst. This study reports the influence of the operating conditions temperature, hydrocarbon inlet height, and oxygen/hydrocarbon molar ratio on the product distribution, in particular on the formation of 1,3‐butadiene. Axial concentration profiles were measured to elucidate the reaction sequence in the fluidized bed.     

Investigation of Ionic Liquids for the Separation of Butanol and Water

Abstract

With the continual rise in the cost of fossil fuel based energy, research into economic and sustainable alternatives is of increasing importance. One significant source of increased cost and demand is the consumption of fossil fuels for automotive fuels. While ethanol has received the most attention as a fuel additive; butanol could be a better direct fuel alternative owing to its physical properties and energy value when compared to ethanol. Commercial butanol is nearly exclusively produced from petroleum feedstocks currently; however, some recent interest has begun to refocus on its generation via fermentation. Unfortunately, this production is limited due to the nature of the process and the use of energy-intensive separation techniques. Ionic liquids are novel green solvents that have the potential to be employed as an extraction agent to remove butanol from the aqueous fermentation media. A hurdle to this potential is the limited availability of solubility data for ionic liquids. This research investigates the phase behavior of two ionic liquids, butanol, and water. Additionally, issues related to the implementation of the investigated ionic liquids are discussed.