Important Intermediate Chemical Research Articles

Process optimization, exergy efficiency, and life cycle energy consumption-GHG emissions of the propane-to-propylene with/without hydrogen production process

Propylene is an extreme important intermediate chemical and it is traditionally produced by steam cracking and fluid catalytic cracking of light oil in petrochemical plants, which will be gradually limited by the increasingly scare oil resources. The propylene production from propane is promising and expected to significantly reduce oil consumption. The process modeling and system analysis methods are used to investigate the techno-environmental performance of the propane dehydrogenation processes with poly-generation of propylene and hydrogen. The propane dehydrogenation processes have great energetic and environmental competitiveness compared with the coal-to-propylene. The propane consumption and direct CO2 emissions are only 1.19 t/t C3H6 and 415 kg/t C3H6. The exergy efficiency of the propane dehydrogenation process with no H2 production is calculated to be 77.61%, while that are as high as 78.68% and 80.73% for the propane dehydrogenation process with H2 recovery rates of 90% and 95%. After subtracting the hydrogen production part, the life cycle energy consumption and GHG emissions of 1 t propylene for the process with H2 recovery rate of 95% are 2.72% and 3.97% lower than that the process with no hydrogen production. This study confirms that development of propane-based propylene and hydrogen production is energetic and environmentally competitive and is therefore promising in olefins industry.

Mechanistic and kinetic investigation on maximizing the formation of levoglucosan from cellulose during biomass pyrolysis

Attempts to understand and control the formation of levoglucosan, as a key bio-oil compound and an important intermediate chemical, during biomass pyrolysis have recently generated a large number of experimental and computational studies. Whilst promising mechanisms have been put forward to explain levoglucosan formation, there has yet to be clarity on the factors that inhibit the stoichiometric yields from cellulose, and, current available mechanisms adopt model compounds of short chain oligosaccharide structures rather than cellulose polymer. In this work, kinetic models describing cellulose (with Degree of Polymerisation DP of 2048) decomposition and levoglucosan formation have been constructed. It was found that temperature and residence time co-ordinately influenced the yield of levoglucosan, i.e. maximum yield can be reached within 80 s at 600 °C, however, around 10 min is required at 550 °C. Anhydro-oligosaccharides greater than DP8 will be generated and then consumed in 60 s with pyrolysis temperatures of 500 °C and over. The results also showed that the current available concerted initiation and depropagation reactions are insufficient to explain the experimentally observed high rates of cellulose depolymerisation and levoglucosan formation, other key factors such as side reactions have to be considered. Additionally, it was found that the rate of levoglucosan generation is independent of the initial cellulose chain length, which is a finding that will facilitate future studies in the area of bioenergy and biomass decomposition.

A pervaporation-crystallization (PC) process for simultaneous recovery of ethanol and sodium pyruvate from waste centrifugal mother liquid

Sodium pyruvate is an important intermediate chemical in the fine chemical, food and pharmaceutical industries. Efficient treatment for waste centrifugal mother liquid (mainly containing ethanol, water and residual sodium pyruvate) generated during the production of sodium pyruvate is highly important to improve the process economy. A pervaporation-crystallization (PC) process is presented in this study for simultaneous recovery of ethanol and sodium pyruvate products from waste centrifugal mother liquid. The PC process contains two-step operation, i.e., the first step is low-temperature pervaporation for water removal, and the second step is cooling crystallization followed by filtration to collect ethanol and crude sodium pyruvate. Mass-produced NaA zeolite membranes show remarkable pervaporation performance for separating ethanol/water/sodium pyruvate mixtures with the water/ethanol separation factor always over 10,000 under various operational conditions. The potential deposition of sodium pyruvate on the outer membrane surface during the long-term use would decrease the total flux. However, the pervaporation performance of NaA zeolite membrane could be easily recovered by water washing regeneration. A pilot-scale study on the PC process for treatment of actual waste centrifugal mother liquid is successfully performed, suggesting the good technical feasibility of PC process for industrial application.

Techno‐economic analysis of 1,4‐butanediol production by a single‐step bioconversion process

Abstract1,4‐Butanediol (1,4‐BDO) is one of the most important intermediate chemicals that is mainly produced using petrochemical routes. Recently, the route to 1,4‐BDO from corn‐based dextrose by single‐step bioconversion has been commercialized. This paper analyzes the bio‐based production route to 1,4‐BDO and establishes the major capital and operating costs associated with production. Bioconversion was found to be the major capital cost component while the hydraulic load from bioconversion and other systems like membrane filtration was found to be the major operating cost component. The process was found to be economically feasible with a minimum sales price (MSP) of 1,4‐BDO of $1.82/kg as compared to a market price of $2.5/kg. In addition, a mechanical vapor recompression scheme for the evaporator benefitted the process, increasing energy efficiency and therefore cost effectiveness. In general, improvements that enable the reduction of hydraulic loads lower the MSP of 1,4‐BDO. The most dramatic cost savings are seen when bioconversion titers are increased. When the bioconversion titers are doubled to 280 g L−1, a 45% reduction in MSP is seen with respect to the baseline process. A sensitivity analysis shows that process is sensitive to feedstock prices but not sensitive to energy prices. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

Extending Catalyst Life in Glycerol-to-Acrolein Conversion Using Non-thermal Plasma.

Booming biodiesel production worldwide demands valorization of its byproduct of glycerol. Acrolein, an important intermediate chemical, can be produced by gas-phase glycerol dehydration catalyzed by solid acids. Because catalysts that lead to high acrolein selectivity usually deactivate rapidly due to the formation of coke that blocks the active sites on their surface, one major challenge of this method is how to extend the service life of the catalyst. Silica-supported silicotungstic acid (HSiW-Si) is a good example of such a catalyst that shows good activity in glycerol dehydration to acrolein initially, but deactivates quickly. In this study, HSiW-Si was selected to probe the potential of using non-thermal plasma with oxygen-containing gas as the discharge gas (NTP-O2) to solve the catalyst deactivation problem. NTP-O2 was found to be effective in coke removal and catalyst regeneration at low temperatures without damaging the Keggin structure of the HSiW-Si catalyst.

Response surface optimization, kinetic study and process design of n-butyl levulinate synthesis

Levulinic acid is an important intermediate chemical, derived from biomass. It is considered platform chemical as its derivatives have numerous applications in various fields. n-butyl levulinate is a levulinic acid derived ester which has wide applications, such as plasticizing, flavouring agent, solvent, and fuel additive. The present work deals with reaction parameters optimization using response surface method for n-butyl levulinate synthesis with Amberlyst 15 catalyst. The process parameters such as acid to alcohol molar ratio, catalyst loading and temperature have been considered. Under optimized conditions, the levulinic acid conversion of 97.03% was obtained. Intrinsic kinetics was studied based on the Langmuir Hinshelwood Hougen Watson model (LHHW) model and the activation energy was found to be 39.89kJ/mol. The commercial viability of the process was evaluated for the capacity of 500kg/h using aspen simulations. Conventional reactive distillation and divided wall reactive distillation schemes were evaluated and cost of production per kg of product was estimated.

Efficient production and secretion of oxaloacetate from Halomonas sp. KM-1 under aerobic conditions

The alkaliphilic, halophilic bacterium Halomonas sp. KM-1 can utilize glucose for the intracellular storage of the bioplastic poly-(R)-3-hydroxybutyric acid (PHB) and extracellular secretion of pyruvate under aerobic conditions. In this study, we investigated the effects of sodium chloride concentration on PHB accumulation and pyruvate secretion in the KM-1 strain and, unexpectedly, observed that oxaloacetate, an important intermediate chemical in the TCA cycle, glycogenesis, and aspartic acid biosynthesis, was secreted. We then further analyzed oxaloacetate productivity after changing the sodium chloride additive concentration, additive time-shift, and culture temperature. In 42-h batch-cultivation experiments, we found that wild-type Halomonas sp. KM-1 secreted 39.0 g/L oxaloacetate at a rate of 0.93 g/(L h). The halophilic bacteria Halomonas has already gained attention for industrial chemical-production processes owing to its unique properties, such as contamination-free culture conditions and a tolerance for high substrate concentrations. Moreover, no commercial scale oxaloacetate production was previously reported to result from bacterial fermentation. Oxaloacetate is an important intermediate chemical in biosynthesis and is used as a health food based on its role in energy synthesis. Thus, these data provided important insights into the production of oxaloacetate and other derivative chemicals using this strain.

Recent advances in the production of γ‐valerolactone from biomass‐derived feedstocks via heterogeneous catalytic transfer hydrogenation

Abstractγ‐valerolactone (GVL) is an important intermediate chemical with a wide range of applications as fuel, fuel additive and as a green solvent which has received a great deal of attentions from both academia and industry. This review aims to summarise the advances in conversion of renewable feedstocks into GVL through heterogeneous catalytic transfer hydrogenation (CTH) with a strong emphasis on discussing preparation, characterisation and performance of the catalysts in order to provide a better understanding of various catalytic systems and also to compare them in terms of catalytic performance. © 2017 Society of Chemical Industry

Surface Lewis acid-promoted copper-based nanocatalysts for highly efficient and chemoselective hydrogenation of citral to unsaturated allylic alcohols

Chemoselective hydrogenation of α,β-unsaturated aldehydes or ketones to unsaturated alcohols (UAs) is one of the key processes for the production of various important intermediate chemicals. In the present work, well-dispersed ZnO-promoted supported copper nanocatalysts were generated from Cu–Zn–Al layered double hydroxide (CuZnAl-LDH) precursors for liquid-phase chemoselective hydrogenation of citral to allylic alcohols (geraniol and nerol isomers). A series of characterizations including XRD, TEM, STEM, XPS, H2-TPR, and Py-IR demonstrated that the microstructure and catalytic performance of as-formed Cu-based nanocatalysts were significantly affected by the incorporation of Zn into catalyst precursors. It was found that the addition of more ZnO to catalysts could result in better metal dispersion and an increase in the surface Cu+/(Cu+ + Cu0) ratio and surface Lewis acid sites. In liquid-phase chemoselective hydrogenation of citral, a high selectivity toward allylic alcohols (>75%) at complete citral conversion was achieved successfully on as-formed non-noble-metal Cu-based nanocatalysts with a Cu/Zn molar ratio of 2 : 1 under mild reaction conditions (e.g. 80 °C, 1.0 MPa). The high efficiency of the catalysts was attributed mainly to both the synergism between Cu0 and Cu+ species and the promotion of surface Lewis acid sites, thereby improving the dissociation of hydrogen and facilitating the adsorption of the citral molecule and the following activation of the carbonyl group during the citral hydrogenation.

Corncob to value‐added chemical transformation by metal/beta zeolite and metal/mesoporous SBA‐15 catalytic pyrolysis

AbstractBACKGROUNDAlthough the pyrolysis of biomass has been investigated by many researchers, there are no data available regarding conversion to value added ester compounds from catalytic corncob pyrolysis at low temperature. In this present research thermal and catalytic cracking of residue corncob was performed at 250 to 600 °C under N2. The performance of two acidic porous catalysts, metal‐beta zeolite and mesoporous SBA‐15, with different metal (Al, Pd and Ni) loadings, were compared with the non‐catalytic reaction.RESULTSThe cracking products were classified into gases, liquid and char. Methane, C5+ and CO2 were the main gas products, while light ester derivatives were the main components in the liquid fraction and these can be important intermediate chemicals. The phenolic compounds were obtained when using low thermal pyrolysis. A reaction temperature of 300 °C with the Al‐SBA‐15 catalyst at a SiO2/Al2O3 mole ratio of 20 was found to be optimal in terms of producing the highest biomass conversion with a high proportion of light esters.CONCLUSIONThe Al‐SBA‐15 (20) catalyst was selective towards producing the light ester 2‐methoxy phenyl acetate (59.4%), which is an important intermediate chemical for production of sweet fruity aromas in the food industry. © 2015 Society of Chemical Industry

Catalytic Conversion of Levulinic Acid and Its Esters to γ-Valerolactone over Silica-Supported Zirconia Catalysts

Abstract Levulinic acid and its esters, important intermediate chemicals produced from biomass resources, were converted to γ-valerolactone via a catalytic transfer hydrogenation process over silica-supported zirconia catalysts. Silica support with a higher surface area provided highly dispersed active zirconium oxide species, which exhibited superior catalytic activity to the conventional ZrO2 catalyst.

Critical review and exergy analysis of formaldehyde production processes

AbstractFormaldehyde is one of the most important intermediate chemicals and has been produced industrially since 1889. Formaldehyde is a key feedstock in several industries like resins, polymers, adhesives, and paints, making it one of the most valuable chemicals in the world. However, not many studies have been dedicated to reviewing the production of this economically important product. In this review paper, we study the leading commercial processes for formaldehyde production and compare them with recent advancements in catalysis and novel processes. This paper compares, in extensive detail, the reaction mechanisms and kinetics of water ballast process (or BASF process), methanol ballast process, and Formox process. The thermodynamics of the reactions involved in the formaldehyde production process was investigated using HSC Chemistry™ software (Outotec Oyj, Espoo, Finland). Exergy analysis was carried out for the natural gas to methanol process and the methanol ballast process for formaldehyde production. The former process was simulated using Aspen HYSYS™ and the latter using Aspen Plus™ software (Aspen technology, Burlington, MA, USA). The yield and product specifications from the simulation results closely matched with published experimental data. The exergy efficiencies of the natural gas to synthesis gas

Biobased Growing Pains

The mid-June gathering of the World Congress on Industrial Biotechnology in Montreal marked the conference’s 10th anniversary. It attracted a record 1,200 attendees, to the delight of the organizer, the Biotechnology Industry Organization. Both the planned agenda and the spontaneous conversations at the event portrayed an industry that is poised to enter those awkward teenage years. When the congress was young, biotechnology experts showed off engineered microbes or new technologies designed to turn abundant biological materials into useful fuels or chemicals. This year, executives focused on mature topics such as feedstock selection and scale-up engineering. The discussions highlighted the challenges inherent in launching a new industry. Succinic acid is one early biobased chemical to reach commercial scale, and a session devoted to it attracted an overflowing crowd. The four-carbon organic acid can be used to make important intermediate chemicals such as adipic acid and 1,4-butanediol. In late 2012, Rev...

Selective adsorption of HMF on porous carbons from fructose/DMSO mixtures

5-Hydroxymethylfurfural (HMF) is an important intermediate chemical for producing valuable chemicals from biomass and can be synthesized with high yield from the dehydration of fructose in dimethyl sulfoxide (DMSO). Here, we investigate the room temperature separation of HMF from DMSO for a cost effective recovery of the product from the reaction mixture that contains unreacted fructose. BP2000, Norit1240, BP1300, BP880 and XC72 were tested as sorbents. BP2000 and Norit1240 exhibit selectivity and capacity for HMF. Depending on relative concentrations, HMF/fructose separation factors up to 45 for BP2000 and 13 for Norit1240 were obtained. Under certain conditions, by increasing the concentration of fructose in the solution, HMF adsorption increased significantly.

Determination of arsenic, antimony, bismuth, germanium, tin, selenium and tellurium in 30% zinc sulfate solution by hydride generation inductively coupled plasma atomic emission spectrometry

C. Rigby and I. D. Brindle, J. Anal. At. Spectrom., 1999, 14, 253 DOI: 10.1039/A808427K