Terms Of Product Distribution Research Articles

Stability, deactivation and regeneration study of a newly developed HZSM-5 and Ni-doped HZSM-5 zeolite catalysts for ethanol-to-hydrocarbon conversion

This work investigates the stability and regeneration of HZSM-5 and Ni/HZSM-5 catalysts in the ethanol-to-hydrocarbon conversion. The catalysts were characterised using different techniques and evaluated at 623 K and 7 h−1 for 96 h TOS with two regeneration cycles. HZSM-5 showed high stability with 100% ethanol conversion, while Ni/HZSM-5 catalysts maintained 100% stability for 48 h before dropping. Regenerated catalysts were comparable to the originals in terms of product distribution, stability, and performance. HZSM-5 preferred BTX, while Ni-doped catalysts favoured C5-C8, C9-C12, and C12+ synthesis. The regeneration process restored catalytic activity, especially for the Ni-doped catalysts, extending their life and reducing replacement costs.

Computational study of propene selectivity and yield in the dehydrogenation of propane via process simulation approach

Abstract Propene is a vital feedstock in the petrochemical industry with a vast range of applications. And there is a continuous rise in propene demand. To gain insight into how the on-purpose method could help meet the demand in the propene market, we investigated the impact of temperature (T) and pressure (P) on product distribution in terms of product yield and selectivity using the process simulation approach. Existing related studies were deployed to identify possible products that could be evaluated in the simulation. In the study, we used Gibbs minimization (with Gibb’s reactor) to predict the likely products obtained at different T and P. The impact of feed purity on product distribution was also evaluated. The study was aided by using the Aspen HYSYS process simulator, while Design Expert was used to search for the optimum conditions for higher conversion, yield, and selectivity. Results obtained for the modeling and simulation of the process show that operating the production process at a lower pressure would favor higher selectivity within the temperature range of 500–600 °C. In comparison, the one run at a higher pressure was predicted to be only promising, showing better selectivity within the range of 550–650 °C. The feed purity significantly impacts the propene amount, especially for one with sulfur impurity, leading to the formation of smaller olefins and sulfide compounds. Our study reveals the importance of reviewing feed purity before charging them into the dehydrogenation reactor to prevent poisoning, coking, and other activities, which do lead to undesired products like methane and ethylene. A catalyst can also be designed to efficiently dehydrogenate the propane to propene at a lower temperature to prevent side reactions.

Hydrodesulphurization of Bonny light crude oil using nano Co–Mo supported on zeolite synthesized from Akoko clay

At present, petroleum remains the single largest global source of nearly all transportation fuel and the main source of industrial chemicals. But the legislative demand for cleaner fuel in automobile worldwide has forced scientists to develop and adopt new technologies to reduce the amount of sulphur in fuel. In this study, a Co–Mo catalyst supported on zeolite synthesized from local clay was developed and tested in hydrodesulphurization reactions, using Bonny light crude oil feed. The Co–Mo was incorporated into the zeolite by wet impregnation method and its activity was evaluated in a batch reactor. The catalyst was characterized and the efficiency was investigated in terms of product distribution and reaction conditions. With a rise in the temperature, the sulphur in the crude oil gets released into the liquid and gas effluents. In the case of gas effluents, the removal of sulphur depends on the reaction temperature, while in the liquid products, the removal of sulphur lies on the reaction time rather than the reaction temperature. The use of this catalyst results in significant upgraded and enhanced oil production with an environmentally friendly fuel, which therefore recommended as an alternative to conventional industrial catalysts.

Mechanochemical Syntheses of Ln(hfac)3(H2O)x (Ln = La-Sm, Tb): Isolation of 10-, 9-, and 8-Coordinate Ln(hfac)n Complexes.

Volatile lanthanide coordination complexes are critical to the generation of new optical and magnetic materials. One of the most common precursors for preparing volatile lanthanide complexes is the hydrate with the general formula Ln(hfac)3(H2O)x (x = 3 for La-Nd, x = 2 for Sm) (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonato). We have investigated the synthesis of Ln(hfac)3(H2O)x using more environmentally sustainable mechanochemical approaches. Characterization of the products using Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, elemental analysis, and powder X-ray diffraction shows substantial differences in product distribution between methods. The mechanochemical synthesis of the hydrate complexes leads to a variety of coordination compounds including the expected hydrate product, the known retro-Claisen impurity, and hydrated protonated Hhfac ligand depending on the technique employed. Surprisingly, 10-coordinate complexes of the form Na2Ln(hfac)5·3H2O for Ln = La-Nd were also isolated from reactions using a mortar and pestle. The electrostatic bonding of lanthanide coordination complexes is a challenge for obtaining reproducible reactions and clean products. The reproducibility issues are most acute for the large, early lanthanides whereas for the mid to late lanthanides, reproducibility in terms of product distribution and yield is less of an issue because of their smaller size and greater charge to radius ratio. Ball milling increases reproducibility in terms of generating the desired Ln(hfac)3(H2O)x along with hydrated Hhfac (tetraol) and free Hhfac products. The results illustrate the dynamic behavior of lanthanide complexes in solution and the solid state as well as the structural diversity available to the early lanthanides.

Production of Pyrolytic Oil from Cassava Peel Wastes

This study investigated the production of pyrolytic oil from cassava peel wastes. Pyrolysis is a very important thermochemical method for converting biomass into biofuel. In recent times, the production of biofuel has taken center stage due to concerns over the sustainability of conventional energy sources. Pyrolysis has received much attention by researchers because it can be used to optimize the production of high calorific value pyrolytic oil. A fixed bed pyrolysing unit was constructed for the production of liquid fuel in this study. Cassava peels were pyrolysed in the reactor. The temperature of reaction was varied to investigate the effect of temperature variation on the product distribution in terms of the percentage weight distribution and the calorific value of the pyrolytic oil. A maximum pyrolytic oil yield of 28.4 wt.% was obtained at 500 °C. The effect of temperature changes on calorific value was also investigated and it was observed that the maximum calorific value of 29.7 MJ/kg was obtained at 600°C.

Design of Low-Cost Ethanol Production Medium from Syngas: An Optimization of Trace Metals for Clostridium ljungdahlii

Syngas fermentation via the Wood-Ljungdahl (WL) pathway is a promising approach for converting gaseous pollutants (CO and CO2) into high-value commodities. Because the WL involves several enzymes with trace metal components, it requires an adequate supply of micronutrients in the fermentation medium for targeted bioprocessing such as bioethanol production. Plackett-Burman statistical analysis was performed to examine the most efficient trace elements (Ni, Mg, Ca, Mn, Co, Cu, B, W, Zn, Fe, and Mo) and their concentrations for Clostridium ljungdahlii on ethanol production. Overall, 1.5 to 2.5 fold improvement in ethanol production could be achieved with designed trace element concentrations. The effects of tungsten and copper on ethanol and biomass production were determined to be the most significant, respectively. The model developed was statistically significant and has the potential to significantly decrease the cost of trace element solutions by 18–22%. This research demonstrates the critical importance of optimizing the medium for syngas fermentation in terms of product distribution and economic feasibility.

Effect of Fe components in red mud on catalytic pyrolysis of low rank coal

Bayer red mud (RM) is a solid waste in alumina production, and the main components is Fe2O3. To investigate the effect of Fe2O3 in RM on pyrolysis of low-rank coal and catalytic upgrading mechanism on tar quality, pyrolysis experiments of pure Fe2O3 and RM mixed with a lignite, Baiyinhua (BYH) coal, were carried out. The results indicate that RM exhibits a similar catalytic effect to Fe2O3 in terms of product distribution and tar composition of coal pyrolysis. At 20% addition of RM or Fe2O3 in coal, the yield of gas and water increases, while that of char decreases; the yield of H2 increases by 38.6% or 37.1%, and the yields of CO and CO2 increase by 58.9%, 78.1% and 24.6%, 44.1%, respectively. GC and GC-MS results prove that the existence of RM or Fe2O3 improve the tar quality, and RM shows a better effect, as the content of heavy components decreases by 11.7% with RM and 5.1% with Fe2O3. Besides, the content of bisphenol, aliphatic hydrocarbon, oxygenated compounds and heteroatomic compounds decrease simultaneously, thus generating more monophenol and naphthalene. Several characterizations show that Fe2O3, as an active component of RM, provides lattice oxygen species to participate in the reaction and changes to Fe3O4 by partial oxidation during the pyrolysis process. TGA results and kinetic analysis of coal pyrolysis illustrate that RM can promote BYH coal pyrolysis and increase the yield of gas and liquid.

Pore-mouth catalysis boosting the formation of iso-paraffins from syngas over bifunctional catalysts

Recent studies confirm that the emerging bifunctional catalysts consisting of metal oxide and zeolites can directly convert syngas into high-quality gasoline, however, the formation mechanism of iso-paraffins and the difference with the conventional FT/zeolite catalyst have not been investigated. Herein, three one-dimensional SAPO zeolites with diverse micropore sizes were synthesized and assembled with ZnAlOx with spinel structure. It was found that ZnAlOx/SAPO-41 and ZnAlOx/SAPO-11 with medium micropore sizes favored the formation of C5–C11 hydrocarbons with a high content of iso-paraffins. The characterizations pointed out that the formation of iso-paraffins over SAPO-11 followed a pore-mouth catalysis mechanism, which means the isomerization of linear hydrocarbons can only take place near the pore mouth region of zeolites. This mechanism only allows the formation of mono-branched iso-paraffins in the C5–C11 range, which are less prone to be cracked than their di-branched isomers. A careful comparative analysis between ZnAlOx/SAPO-11 and Co/H-meso-ZSM-5 was also made in terms of product distribution, activity, and stability.

PENENTUAN RUTE DISTRIBUSI KERAMIK DENGAN METODE SAVING MATRIX (STUDI KASUS: PT. LUCRO INDO JAYA)

ABSTRACTDistribution is part of logistics, with a fundamental function for the company. Distribution made from a source to various destinations makes this activity quite complex because the distribution channels that are adrift with a long-distance make the number of costs incurred for shipping. This study aims to minimize the delivery distance traveled in the distribution of ceramics to more than one retail by using the saving matrix method. The saving matrix method can schedule vehicles to distribute products from the central warehouse to several shipping routes. This research was conducted using data in the form of ceramic supply at the company, retail demand data, distance data, and shipping cost of ceramics in January-December 2018 with a total of 10 (ten) customer destinations located in Tangerang-Jakarta. The saving matrix method is optimized by using the method of Farthest Insert, Nearest insert and Nearest Neighbor in determining vehicle scheduling by sorting shipments that are considered more optimal. The results of this study are obtained savings of 14.5% with a total distance that was previously 302.9 km to 258.9 km and savings in shipping costs by 15% which previously was Rp 1,756,150,000 to Rp 1,501,047,326. The use of the saving matrix method is able to improve the order of shipping routes of the company's distribution so that it reduces shipping mileage and reduces the company's operating costs in terms of product distribution.Keywords: distribution, distance minimization, routing, saving matrixABSTRAKDistribusi merupakan bagian dari logistik, dengan fungsi fundamental bagi perusahaan. Pendistribusian yang dilakukan dari suatu sumber keberbagai tempat tujuan menjadikan kegiatan ini cukup komplek, dikarenakan jalur distribusi yang terpaut dengan jarak yang panjang menjadikan besarnya biaya yang dikeluarkan untuk pengiriman. Penelitian ini bertujuan meminimumkan jarak pengiriman yang ditempuh dalam distribusi keramik ke lebih dari satu retail dengan menggunakan metode saving matrix. Metode saving matrix dapat menjadwalkan kendaraan untuk melakukan pendistribusikan produk dari gudang central ke beberapa rute pengiriman. Penelitian ini dilakukan dengan menggunakan data berupa persediaan (supply) keramik pada perusahaan, data permintaan (demand) kebutuhan retail, data jarak dan biaya pengiriman keramik pada bulan Januari-Desember 2018 dengan total 10 (sepuluh) tujuan pelanggan yang berlokasi di Tangerang-Jakarta. Metode saving matrix dioptimalkan dengan penggunaan metode Farthest Insert, Nearest insert dan Nearest Neighbor dalam menentukan penjadwalan kendaraan dengan mengurutkan pengiriman yang dinilai lebih optimal. Hasil dari penelitian ini adalah diperolehnya penghematan sebesar 14,5% dengan total jarak yang sebelumnya 302,9 km menjadi 258,9 km dan penghematan biaya pengiriman sebesar 15% yang sebelumnya sebesar Rp 1.756.150.000 menjadi Rp 1.501.047.326. Penggunaan metode saving matrix mampu memperbaiki urutan pengiriman rute distribusi perusahaan sehingga mengurangi jarak tempuh pengiriman dan mengurangi biaya operasional perusahaan dalam hal distribusi produk.Kata Kunci: distribusi, minimasi jarak, routing, saving matrix

Influence of temperature on products from fluidized bed pyrolysis of wood and solid recovered fuel

The fluidized bed fast pyrolysis of two different kinds of fuels, namely, wood pellets (WP) and solid recovered fuel (SRF) pellets made up of a municipal solid waste by ECONWARD TECH, S.L. (EP) has been carried out. Thus, the analysis of the influence of pyrolysis reactor temperature (600–800 °C) and fuel type in terms of product distribution, e.g. gases, char and tar has been performed. The conditions used in this work are of special interest for the gasification in fluidized beds, in which fast pyrolysis plays a relevant role as it is the first step of fuel conversion. The gas composition was continuously recorded and the tar samples collected during the experiments were analyzed by GC technique. The higher ash content in the EP enhanced charring and decarboxylation reactions, which greatly influenced the distribution of the gaseous products leading to a high CO2 yield. Tar composition was also affected by the constituents of the fuels used, with the content of phenolic compounds in the EP tar obtained at 650 °C being particularly low at the expense of a higher light aromatic content. The rise in temperature decreased the fraction of phenolic compounds and led to a gradual formation of light and heavy polycyclic aromatic hydrocarbons (PAHs), with naphthalene being the major compound in tars of both fuels, WP and EP, at high temperature. The results can be used to derive pyrolysis sub-models for fluidized bed gasification modeling.

Co-aromatization of methane with propane over Zn/HZSM-5: The methane reaction pathway and the effect of Zn distribution

The co-aromatization of methane with propane is investigated using Zn/HZSM-5 as the catalyst at 400 °C. The presence of methane has a pronounced effect on the product distribution in terms of improved formation of phenyl rings and substitution groups of aromatic species. Isotopic labeling and solid-state NMR spectroscopy studies reveal that the favored site for methane incorporation varies at different stages along the co-aromatization reaction, from the benzylic sites at the initial stage to the phenyl rings and then substitution groups as the reaction proceeds. SIMS spectroscopy of the involved reaction intermediates suggests the formation of C4 species over the Zn sites that are bonding to the oxygen atoms of the zeolite framework, which is supported by theoretical calculations. The interaction between Zn species and the zeolite framework is also confirmed by XAS and changes in coordination environments are identified through XANES and solid-state NMR spectroscopy. The redistribution of Zn during the reaction is observed on the surface of the zeolite support. Scanning transmission X-ray microscopy images show that Zn is rich in the inner pores compared with the external surface of the catalyst particles in the pristine catalysts. XANES and XPS spectra demonstrate that the Zn concentration increases on the external surface after the reaction, a conclusion that is further supported by the theoretical study. The Zn redistribution might be among the reasons for methane participation pathway alternation during the co-aromatization, since the Zn species located within the inner pores and on the external surface might prefer to catalyze the methane incorporation to the phenyl rings and substitution groups of the formed aromatics, respectively.

Influence of coker-derived liquids on coking performance of Venezuelan heavy oil residue

Coking technological improvements are required to effectively upgrade/refine extra-heavy oil residues. The influence of types and blending ratios of coker-derived liquids on the coking performance of Venezuelan residue was studied in terms of product distribution and coke morphology. Blending of the coker diesel distillates (200–350 °C) with the residues was not suggested, given the negative interactions at all blending ratios (0–0.6) as concluded from coke yield analysis. Blending of the coker gas oil improved the coke quality and inhibited the coke formation. The recycle of heavy coker gas oil (430 °C+) at a blending ratio of 0.3 was most favorable.

Co-aromatization of methane with olefins: The role of inner pore and external surface catalytic sites

The co-aromatization of methane with olefins is investigated using Ag-Ga/HZSM-5 as the catalyst at 400 °C. The presence of methane has a pronounced effect on the product distribution in terms of increased average carbon number and substitution index and decreased aromatic carbon fraction compared with its N2 environment counterpart. The participation of methane during the co-aromatization over the Ag-Ga/HZSM-5 catalyst diminishes as the co-fed olefin feedstock molecule becomes larger, from 1-hexene to 1-octene and 1-decene, in diameter. The effect of suppressed methane participation with larger olefinic molecules is not as significant when Ag-Ga/HY is employed as the catalyst, which might be attributed to the larger pore size of HY that gives more room to hold olefin and methane molecules within the inner pores and reduces the diffusion limitation of olefin molecules. The effect of olefin feedstock on the methane participation during the co-aromatization over Ag-Ga/HZSM-5 is experimentally evidenced by 13C and 2D NMR. The incorporation of the methane carbon atoms into the phenyl ring of product molecules is reduced significantly with larger co-fed olefins, whereas its incorporation into the substitution groups of the formed aromatic molecules is not notably affected, suggesting that the methane participation in the phenyl ring formation might preferably occur within inner pores, while its incorporation into substitution groups may mainly take place on external catalytic sites. This hypothesis is well supported by the product selectivity obtained over Ag-Ga/HZSM-5 catalysts prepared using conventional ZSM-5, ZSM-5 with the external catalytic sites deactivated, nanosize ZSM-5, ZSM-5 with a micro/meso pore structure and ZSM-5 with the inner pores blocked, and further confirmed by the isotopic labeling studies.

Effects of torrefaction temperature and acid pretreatment on the yield and quality of fast pyrolysis bio-oil from rice straw

This study investigated the effects of torrefaction temperatures and dilute acid pretreatment on the quality of pyrolysis bio-oil and the distribution toward gaseous, liquid bio-oil, and char products from rice straw. Torrefaction of rice straw was conducted at different temperatures (225°C, 250°C, and 275°C) for 30minutes in a Py-GC/MS reactor. After the torrefaction process was completed, fast pyrolysis of torrefied rice straw was then performed at temperatures of 450°C, 500°C and 550°C with a heating rate of 1000°C/s and held for 20seconds in the same micropyrolysis reactor. The results showed that the decrease of pyrolysis bio-oil, gas, and water, are observed when the torrefaction temperature increases. However, the decreasing trend of pyrolysis char yield was observed when the torrefaction severity increases at pyrolysis temperatures 450°C and 500°C, but an increasing trend was noticeable at pyrolysis temperature 550°C. The phenolic components in pyrolysis bio-oil from torrefied rice straw were lower compare to raw rice straw. The torrefaction process helps improve the quality of pyrolysis bio-oil in terms of reducing some water, acid, and oxygenated species. The torrefaction temperature of 225°C with the pyrolysis temperature of 550°C is indicated as the optimum condition in our study. Additionally, the removal of mineral content from rice straw promoted higher yields of pyrolysis bio-oil, particularly levoglucosan. The acid pretreatment method also improved the pyrolysis product distribution in terms of enhancing bio-oil yield and reducing water, gas, and char.

Pyrolysis of automotive shredder residue in a bench scale rotary kiln

Automotive shredder residue (ASR) can create difficulties when managing, with its production increasing. It is made of different type of plastics, foams, elastomers, wood, glasses and textiles. For this reason, it is complicated to dispose of in a cost effective way, while also respecting the stringent environmental restrictions. Among thermal treatments, pyrolysis seems to offer an environmentally attractive method for the treatment of ASR; it also allows for the recovery of valuable secondary materials/fuels such as pyrolysis oils, chars, and gas. While, there is a great deal of significant research on ASR pyrolysis, the literature on higher scale pyrolysis experiments is limited. To improve current literature, the aim of the study was to investigate the pyrolysis of ASR in a bench scale rotary kiln. The Italian ASR was separated by dry-sieving into two particle size fractions: d<30mm and d>30mm. Both the streams were grounded, pelletized and then pyrolyzed in a continuous bench scale rotary kiln at 450, 550 and 650°C. The mass flow rate of the ASR pellets was 200–350g/h and each test ran for about 4–5h. The produced char, pyrolysis oil and syngas were quantified to determine product distribution. They were thoroughly analyzed with regard to their chemical and physical properties. The results show how higher temperatures increase the pyrolysis gas yield (44wt% at 650°C) as well as its heating value. The low heating value (LHV) of syngas ranges between 18 and 26MJ/Nm3dry. The highest pyrolysis oil yield (33wt.%) was observed at 550°C and its LHV ranges between 12.5 and 14.5MJ/kg. Furthermore, only two out of the six produced chars respect the LHV limit set by the Italian environmental regulations for landfilling. The obtained results in terms of product distribution and their chemical-physical analyses provide useful information for plant scale-up.

Influence of pressure (100 Pa–100 Mpa) on the pyrolysis of an alkane at moderate temperature (603 K–723 K): Experiments and kinetic modeling

Confined pyrolysis of n-octane was performed in a closed, constant-pressure gold reactor at pressure ranging 1 MPa–70MPa, temperature between 603K and 723K and residence times from 1h to 1 month. The main products of reaction are n-alkanes of molecular weight lower than n-octane and branched alkanes of molecular weight higher than n-octane. Alkenes are minor products. At moderate temperature (603K–623K) the conversion of n-octane increases with pressure up to a maximum and then decreases (at constant duration of pyrolysis). For higher temperature (723K) the conversion increases continuously with increasing pressure. A mechanism consisting of 182 free-radical reactions is set up and used to model these experimental results (1–70MPa) as well as those obtained in a previous study at very low concentration (100Pa diluted in inert gas, total pressure 0.15MPa). The agreement between the experimental data and simulation results is satisfactory in terms of product distribution and conversion of n-octane in a wide range of pressure (100Pa to 70MPa). Some mechanistic explanations concerning the effect of pressure are proposed.

Reductive Catalytic Fractionation of Corn Stover Lignin

Reductive catalytic fractionation (RCF) has emerged as an effective biomass pretreatment strategy to depolymerize lignin into tractable fragments in high yields. We investigate the RCF of corn stover, a highly abundant herbaceous feedstock, using carbon-supported Ru and Ni catalysts at 200 and 250 °C in methanol and, in the presence or absence of an acid cocatalyst (H3PO4 or an acidified carbon support). Three key performance variables were studied: (1) the effectiveness of lignin extraction as measured by the yield of lignin oil, (2) the yield of monomers in the lignin oil, and (3) the carbohydrate retention in the residual solids after RCF. The monomers included methyl coumarate/ferulate, propyl guaiacol/syringol, and ethyl guaiacol/syringol. The Ru and Ni catalysts performed similarly in terms of product distribution and monomer yields. The monomer yields increased monotonically as a function of time for both temperatures. At 6 h, monomer yields of 27.2 and 28.3% were obtained at 250 and 200 °C, respec...

Reactive force field simulation studies on the combustion behavior of n-octanol

n-Octanol is a new promising fuel which is considered as an alternative to conventional diesel. In order to understand the combustion characteristics of n-octanol, reactive molecular dynamics (ReaxFF MD) simulation of n-octanol has been carried out at temperatures from 2000 to 4000K with equivalence ratios ranging from 0.5 to 2.0. Ethylene and formaldehyde have been found to be major intermediates in the oxidation of n-octanol which is in agreement with the available experimental data. Reaction mechanisms have been proposed for the formation of major intermediates (C2H4 and CH2O) and final products (CO and CO2) from where it is revealed that intermediates are mainly consumed by the build-up of hydroxyl and hydroperoxyl radicals. It was observed that the CO and CO2 formation from formaldehyde and ethylene starts with the attack of molecular oxygen or hydroxyl radical or hemolytic OH bond cleavage. Overall, a good qualitative agreement with the available experimental data in terms of product distribution has been found. The results indicate that ReaxFF MD simulations can give a detailed description of the reaction mechanism and product distribution for the combustion for oxygenated fuel such as octanol.

Effectiveness of Different Transition Metal Dispersed Catalysts for In Situ Heavy Oil Upgrading

Ultradispersed particles of a size less than 100 nm for in situ catalytic upgrading have been reported to outperform the augmented catalytic upgrading achieved by incorporating pelleted refinery catalyst to the horizontal production well of the toe-to-heel air injection (THAI) process. Hydroconversion of heavy oil was carried out in a stirred batch reactor at 425 °C, 50 bar (initial H2 pressure), 900 rpm, and 60 min reaction time using a range of unsupported transition metal (Mo, Ni, and Fe) catalysts. The effect of metal nanoparticles (NPs) was evaluated in terms of product distribution, physical properties, and product quality. The produced coke and recovered catalysts were also studied. The levels of API gravity and viscosity of the upgraded oils observed with the NPs was approximately 21° API and 108 cP compared with thermal cracking alone (24° API and 53.5 cP); this moderate upgrade with NPs is due to the lack of cracking functionality offered by supports such as zeolite, alumina, or silica. However,...

Simultaneous synthesis of mixtures of lactulose and galacto-oligosaccharides and their selective fermentation

Lactulose and galacto-oligosaccharides (GOS) are well recognized prebiotics derived from lactose. In the synthesis of lactulose with β-galactosidases GOS are also produced, but the ratio of lactulose and GOS in the product can be tuned at will, depending on the operation conditions, so to obtain an optimal product distribution in terms of prebiotic potential. The selectivity of fermentation of each carbohydrate alone as well as mixtures of both was determined using pH-controlled anaerobic batch cultures with faecal inoculum. Within the experimental range considered, lactulose/GOS molar ratio of 4 resulted in the highest selectivity for Bifidobacterium and Lactobacillus/Enterococcus, so this ratio was selected as the target for the synthesis of lactulose from fructose and lactose with Aspergillus oryzae β-galactosidase. Synthesis was optimized using response surface methodology, considering temperature, initial concentrations of acceptor sugars and fructose/lactose molar ratio as key variables, with the aim of maximizing lactulose yield at the optimal product distribution in terms of prebiotic potential (lactulose/GOS molar ratio of 4). Under optimal conditions (50°C, 50%w/w total initial concentrations of sugars and fructose/lactose molar ratio of 6.44), lactulose yield of 0.26g of lactulose produced per g of initial lactose was obtained at the optimal product distribution.