Docosane Research Articles

Techno-economic evaluation of CO2-rich natural gas dry reforming for linear alpha olefins production

The South China Sea is rich in oil and gas resources, accounting for one-third of China's total oil and gas resources. However, the natural gas there has high concentration of carbon dioxide (CO2), so decarbonization process is required, which will cause a large amount of energy loss and carbon emission. To realize direct, efficient and high-value utilization of CO2-rich nature gas in the South China Sea, this paper designs a conceptual route which integrates CO2-rich natural gas dry reforming with Fischer-Tropsch to olefins (FTO) technology to produce high value-added linear alpha olefins (LAO) products. Material and energy balance of the integrated system is calculated via Aspen Plus modelling. The energy efficiency, carbon efficiency and economic performance of this integrated system is evaluated. The results show that the net CO2 emission of this system is only 0.06 ton-CO2/ton-product and the carbon efficiency of the system is up to 60.8%; the system's NPV is positive and much higher than zero, indicating that the system is fairly risk-resistant and economically feasible. This technical route blazes a new way for direct conversion and utilization of CO2-rich nature gas, and has great potential for development. It not only realizes the conversion and utilization of CO2, but also produces high value-added LAO products, which will alleviate the shortage of LAO production in China.

The Characteristics of Ambient Non-Methane Hydrocarbons (NMHCs) in Lanzhou, China

Non-methane hydrocarbons (NMHCs) from four sampling sites in Lanzhou, a petrochemical industrialized city in northwest China, was sampled by stainless steel canisters and measured by gas chromatography–mass selective detection/flame ionization detection (GC–MSD/FID) in May and June of 2017. Based on these results, the contributions of NMHCs to the ozone (O3) and secondary organic aerosols (SOA), differences in tracer ratios, and source apportionment by principal component analysis (PCA) were analyzed. The results showed that the total NMHCs concentration in Lanzhou was 48.4 ± 48.3 ppbv (parts per billion by volume) during the observation and it was higher in May (78.6 ppbv) than in June (37.8 ppbv); the highest NMHCs concentration was observed in industrial areas. Alkanes were the dominant group at all sites in Lanzhou and account for more than 60% of the NMHCs, while isopentane, n-butane n-pentane, propane and ethane were the major compounds. Additionally, the NMHCs in Lanzhou have made great contributions to O3 and SOA generation and the S1 site of the industrial area contributed the most to both of them. Propene, toluene, ethylbenzene and n-pentane were found to be more reactive with relatively high contributions to ozone formation. Aromatics and high carbon alkanes were major contributors to SOA formation potential (SOAp) (i.e., toluene, m,p-xylene, dodecane, undecane, n-tanane, benzene and ethylbenzene) in Lanzhou. Based on the specific volatile organic compounds (VOCs) ratio method and the PCA modem, the observation sites in Lanzhou were greatly affected by the surrounding industrial areas. The sources consisted of petrochemical industry, vehicle emissions, solvent usage and combustion sources, which contributed to 33.9%, 31.6%, 19.2% and 7.9% of the total monitored NMHCs, respectively. From different sites, though the influence of regional transport was not very significant on the whole, it also affected the NMHCs of nonindustrial areas based on the ratio of xylene to ethyl-benzene (X/E), especially the S4 site; vehicle emission was less important compared to sources from petrochemical industries in S1, as characterized by relatively higher toluene to benzene (T/B) ratios. However, vehicle emission has significant influence on NMHCs in S4. Overall, local emissions are the main source of NMHCs in Lanzhou and the petrochemical industry has a great influence on the distribution of NMHCs in the whole region.

Facile Synthesis of Uniform Metal Carbide Nanoparticles from Metal-Organic Frameworks by Laser Metallurgy.

We report the fast and efficient conversion of metal-organic frameworks (MOFs) to phase pure transition-metal carbide (TMC) nanoparticles with uniform size using laser as the energy source, consuming only 6 W power. Nanoparticles of HfC, ZrC, TiC, V8C7, α-MoC, Cr3C2, and FeCx with homogeneous sizes (varied between 6 and 20 nm) were successfully produced, among which HfC and ZrC nanoparticles were obtained, for the first time, with sizes less than 10 nm and in the pure phase. This method was operated directly in air, in stark contrast to traditional furnace heating and laser spray methods, where a protective atmosphere is required. The use of MOFs allowed us to precisely tune the composition of TMC nanoparticles by dialing in the right type and desirable amounts of organic linkers. FeCx nanoparticles doped with various percentages of nitrogen atoms were synthesized for the Fischer-Tropsch reaction without any pretreatment or activation. Extremely high iron time of yield (FTY) values were observed, 415 and 550 μmol gFe-1 s-1 (with addition of K), in a 40 h test without any decay in performance. A high olefin to paraffin ratio was achieved for C2 to C11 products, where the ratio for C3 was higher than 10.

Conversion of hydrous bio-ethanol on ZnxZryOz catalyst to renewable liquid chemicals and additives to gasoline

The conversion of ethanol on the ZnxZryOz catalyst was studied over a wide range of operating conditions to determine the possibility of producing organic liquid (olefins, aromatics and oxygenates). The content of water in the feed was found to be the key parameter. At ≥60 wt% water, no organic liquid is formed. As water content decreased, the yield of organic liquid increased. Furthermore, increasing pressure increased the yield of organic liquids. Experiments conducted at increasing residence time indicated that ethanol was first converted to oxygenates then to aromatics and higher olefins (C5–C11) with propylene, ethylene, carbon dioxide and hydrogen as the main by-products. Increasing temperature at high residence time (WHSV = 0.8 h−1) decreased the yield of liquid oxygenates while increasing the yield of aromatics and higher olefins. A tentative scheme of reactions was proposed considering the special nature of the ZnxZryOz catalyst with balanced basic-acidic sites. The catalyst was stable, tested for >300 h. Tail gas containing light olefins, mainly propylene and ethylene, was converted by oligomerization on a commercial H-ZSM-5 catalyst to higher olefins (>90%) and aromatics at high conversion (>90%). The organic liquid from the two reactors can be used as feedstock for chemicals or as blending stock for gasoline.

Comparative study of a vitrinite-rich and an inertinite-rich Witbank coal (South Africa) using pyrolysis-gas chromatography

This study aims to compare iso-rank vitrinite-rich and inertinite-rich coal samples to understand the impact of coal-forming processes on pyrolysis chemistry. A medium rank C bituminous coal was density-fractionated to create a vitrinite-rich and an inertinite-rich sub-sample. The vitrinite-rich sample has 83 vol% total vitrinite (mineral-matter-free basis), whereas the inertinite-rich counterpart has 66 vol% total inertinite. The vitrinite-rich sample is dominated by collotelinite and collodetrinite. Fusinite, semifusinite, and inertodetrinite are the main macerals of the inertinite-rich sample. Molecular chemistry was assessed using a pyrolysis gas chromatograph (py-GC) equipped with a thermal desorption unit coupled to a time of flight mass spectrometer (MS) (py-GC/MS) and solid-state nuclear magnetic resonance (13C CP-MAS SS NMR). The pyrolysis products of the coal samples are generally similar, comprised of low and high molecular weight alkanes, alkylbenzenes, alkylphenols, and alkyl-subtituted polycyclic aromatic hydrocarbons, although the vitrinite-rich sample is chemically more diverse. The lack of diversity exhibited by the inertinite-rich sample upon pyrolysis may be interpreted to suggest that major components were heated in their geologic history. Based on the 13C CP-MAS SS NMR analysis, the inertinite-rich sample has a greater fraction of phenolics, reflected in the py-GC/MS results as substituted and unsubstituted derivatives. The greater abundance of phenolics for the inertinite-rich sample may suggest a fire-related origin for the dominant macerals of this sample. The C2-alkylbenzene isomers (p-xylene and o-xylene) were detected in the pyrolysis products for the vitrinite-rich and inertinite-rich samples, though more abundant in the former. The presence of these in both samples likely reflects common source vegetation for the dominant vitrinite and inertinite macerals.

CO2 hydrogenation to light olefins over Cu-CeO2/SAPO-34 catalysts: Product distribution and optimization

The direct conversion of carbon dioxide into hydrocarbons is a very desirable but difficult approach for achieving lower value-added olefins with minimal CO selectivity. In this effort, we report the direct conversion of CO2 into light olefins on a Cu/CeO2 hybrid catalyst mixed with SAPO-34 zeolite. The samples are characterized by N2 sorption, XRD, TEM, SEM, NH3-TPD and H2 -TPR. The results showed that the acidity of modified zeolite had decreased. The response surface methodology has been used to optimize the operating parameters (temperature and space velocity (SV)) of process. A high olefin selectivity of 70.4% has been obtained on CuCe/SAPO-34 at H2/CO2 =3, 10 h, 382.46 °C, 17.33 L/g.h and 20 bar. The optimum operating conditions for multiple responses have also been achieved. The optimal values are T = 396.26 °C and SV = 5.80 L/g.h. Under these conditions, the predicted olefin and CO selectivity and CO2 conversion are 61.83%, 57.11% and 13.15%, respectively. Multiple optimization outputs are outstanding for obtaining the suitable operating conditions.

Managerial Approach to the Main Risks Associated with the Use of Catalytic Cracking Plants

The unprecedented technological development of the last decades has spanned a number of top industrial areas and industries, characterized by the use of highly technological and complex technological equipment in the context of the pursuit of demanding technological processes. The different exploitation of the involved lines and technological installations, assuming their quasi-continuous operation, by significantly reducing the weight of stops caused by various failures / failures, in the circumstances of adequately protecting the health of staff and the population, as well as in the context of environmental conservation, requires ensuring and maintaining high levels of reliability and technical security. Industrial practice has shown that no matter how much they invest to achieve and maintain a high level of the reliability of a technological system, an ideal reliability cannot be ensured, a system that does not degrade in time. The reliability of a technological system is determined by all the factors involved in its implementation - the design, realization and exploitation of the system. The concepts of technical and technical risk are indissolubly linked to the notion of major damage. This is one of the possible consequences of a technical accident and essentially involves both the cessation of the system's ability to properly perform its functions and the alteration or disappearance of its physical integrity in the context of particularly serious consequences on the state of technological equipment related, health and / or life of the staff employed and possibly the population, the quality of the environment or the equilibrium of the ecosystem. This paper considers the analysis of the risks associated with the activity of the catalytic cracking plant at the Lukoil Ploieşti refinery and presents the actions applied to the equipment and the measures that are applied to prevent the occurrence of any hazards and accidents on the plant. The purpose of these measures applied to catalytic cracking equipment is to protect employees and the population. Catalytic cracking is one of the basic processes in the Petrotel Lukoil refinery, which ensures the conversion of high-octane petroleum fractions into high octane gas and high olefin gas needed for the petrochemical industry, and will probably represent the catalytic process with the greatest share in processing for long time oil.

Dimethyl Ether Conversion to Light Olefins on Zeolite Catalysts: Effect of MFI-Type Zeolite Nature and SiO2/Al2O3 Molar Ratio on Catalyst Efficiency

The physicochemical and catalytic properties of magnesium-containing zeolite catalysts based on MFI-type zeolites (ZSM-5 and CBV) were compared. The presence of larger mesopores volume in MgCBV was found to decrease selectivity towards light olefins. In order to improve the catalytic properties of MgCBV, the effect of SiO2/Al2O3 molar ratio of CBV (SiO2/Al2O3 = 30, 55, 80 and 300) on its physicochemical and catalytic properties in the reaction of the dimethyl ether (DME) into light olefins was studied. Increasing SiO2/Al2O3 molar ratio from 30 to 80, was shown not change practically the DME conversion and olefin selectivity, but under a SiO2/Al2O3 molar ratio of 300, DME conversion significantly reduces, olefin selectivity increases, while the ethylene/propylene ratio decreases twice. By changing residence time, DME conversion increases under high total light olefins selectivity, while the ethylene/propylene ratio raises with increasing residence time.

First Investigation of Seasonal Concentration Behaviors and Sources Assessment of Aliphatic Hydrocarbon in Waters and Sediments from Wadi El Bey, Tunisia.

The contents, composition profiles, and sources of aliphatic hydrocarbons were examined in surface sediment and water samples collected from Wadi El Bey, in Tunisia, during different year seasons in 14 stations receiving domestic effluent, industrial discharge, and agricultural drainage wastes. The target substances were analyzed by gas chromatography coupled with mass spectrometric detection (GC/MS). Total concentrations of n-alkanes (n-C14-n-C38) ranged from 0.08 ± 0.01 to 18.14 ± 0.1µg/L in waters and 0.22 ± 0.04 to 31.9 ± 24.6µg/g in sediments, while total aliphatic fraction ranged from 0.08 ± 0.01 to 196 ± 140µg/L in waters and 0.22 ± 0.04 to 1977 ± 1219µg/g in sediments, which means that almost all sites were affected by hydrocarbon contents in sediments exceeding the recommended limit (100µg/g). Various diagnostic indices (ADIs) were used to identify the hydrocarbon sources, namely the concentration ratios of individual compounds (n-C17/pristane, n-C18/phytane, pristane/phytane, n-C29/n-C17, n-C31/n-C19) as well as cumulative quantities (Carbon Preference Index, natural n-alkanes ratio, terrigenous/aquatic compounds ratio, unresolved complex mixture percentage, low molecular weight vs. high molecular weight homologues, Alkane Proxy and Terrestrial Marine Discriminants). In general, these indexes indicated that the origin of aliphatic hydrocarbons affecting sediments and waters of Wadi El Bey were linked to both biogenic and petrogenic inputs, attesting the impact of plankton and terrestrial plants and of oil contamination, respectively. The average carbon chain length computation (ACL), used to further index the chemical environment, ranged from 25.5 to 31.1 in sediments and 47.9-116 in waters. This finding could depend on the severe disturbances suffered by the ecosystem as a consequence of heavy anthropogenic inputs. Petroleum contamination associated with high eutrophication rates in Wadi El Bey must be strictly controlled, due to possible harmful effects induced on ecosystem and humans.

Engineering of Surface Environment of Pd Nanoparticle Catalysts on Carbon Support with Pyrene-Thiol Ligands for Semihydrogenation of Alkynes.

A new type of pyrene-thiol derivative-modified Pd nanoparticle (NP) catalyst on a carbon black support for the efficient semihydrogenation of alkynes to alkenes is reported herein. Colloidal Pd NPs surrounded by pyrene-thiol modifiers were prepared using the two-phase Brust method followed by impregnation of carbon black materials. Based on the structural characterization of the prepared catalyst (PyC12S-Pd/VC) by NMR, UV-vis, FT-IR, TEM, HAADF-STEM, Pd K-edge XAFS, XRD, N2 adsorption, and XPS, we show that highly dispersed Pd NPs are immobilized on the catalysts via π-π interaction between pyrene groups bound to the Pd NPs and carbon black supports. PyC12S-Pd/VC efficiently catalyzes the alkyne semihydrogenation reaction while maintaining high alkene selectivity; an alkene selectivity of 94% is attained at 98% conversion after 5 h of reaction, and the selectivity was retained around 80% in 10 h of reaction. This performance is superior to that of a catalyst without pyrene groups and that of a commercial Lindlar catalyst. The steric hindrance of pyrene groups restricts access of the substrates to Pd NP surfaces, suppressing the unfavorable overhydrogenation of alkenes to alkanes, which is revealed by the solvent and substrate dependency on the catalytic performance and a DFT calculation study. Furthermore, the high selectivity and stability of PyC12S-Pd/VC are caused by the strong interaction between pyrene groups and carbon supports, which prevents the separation of pyrene modifiers and the leaching or sintering of Pd NPs during the catalytic reaction. It is demonstrated that the combination of Pd NPs, pyrene-thiol modifiers, and carbon supports offers high activity, alkene selectivity, and stability in the semihydrogenation reaction.

Reduction Kinetics of Perovskite Oxides for Selective Hydrogen Combustion in the Context of Olefin Production

Chemical looping represents a novel approach for generating light olefins in which thermal cracking or catalytic dehydrogenation is coupled with selective hydrogen combustion (SHC) by a metal oxide redox catalyst, which enables autothermal operation, increased per‐pass conversion, and greater‐than‐equilibrium yields. Recent studies indicate that Na2WO4‐promoted perovskite oxides are effective redox catalysts with high olefin selectivity. Herein, kinetic parameters, rates, and reaction models for the reduction of unpromoted and Na2WO4‐promoted CaMnO3 redox catalysts by H2, C2H4, and C2H6, is reported. Reduction rates of CaMnO3 under ethylene and ethane are significantly lower than under H2. Model fitting of reduction kinetics show good agreement with reaction order–controlled models for CaMnO3 reduction and predict greater oxygen site dependence and higher activation energy for CaMnO3 reduction by C2H4 as compared with H2. Avrami–Erofe'ev nucleation and growth models provide the best fit to the reduction of Na2WO4/CaMnO3 in H2 and in C2H4. After Na2WO4 promotion, the reduction rate of CaMnO3 is three orders of magnitude lower in ethylene in comparison to hydrogen, consistent with its superior selectivity to hydrogen combustion. The models developed can be applied toward reactor design and optimization in the context of enhanced olefin production via SHC under a cyclic redox scheme.

Direct CO2 hydrogenation to light olefins by suppressing CO by-product formation

We evaluate the direct CO2 conversion to light olefins reaction via a hybrid catalyst of In2O3/ZrO2 metallic oxide and zeolite SAPO34 components. On this catalyst, it can realize producing high light olefins selectivity of 77.59% via a direct tandem catalysis process, that is, the formed methanol on the oxygen vacancies surface of In2O3/ZrO2 in the first step will continue passing through the SAPO34 zeolite channel, where it is changed into light olefins simultaneously. Even there are many studies focused on this tandem catalysis reaction via bi-functional catalyst in recent years, however, to reduce the poisonous byproduct CO is still in a big challenge. In this reaction, large amounts of poisonous CO will be easily formed from reverse water gas shift reaction. Therefore, in our research, by optimizing the reaction, the catalyst can suppress the undesirable CO formation obviously. It shows good potential leading to scale-up cause of the outstanding reaction performance and its friendly-environment properties.

Nanosecond pulsed discharge-driven non-oxidative methane coupling in a plate-to-plate electrode configuration plasma reactor

In this work, we establish a set of reactor operation guidelines for efficient non-oxidative methane coupling (i.e., high olefins yield) in nanosecond pulsed discharges and plate-to-plate electrode configuration. The reactor performance analysis suggests that the operating conditions directly affect the bulk gas temperature, which in turn determines the plasma resistance and, subsequently, the energy channeled into the discharge. High performance is attained only at proper load-impedance matching, i.e. when operating in spark regime and applying i) moderate pulse frequencies (≤20 kHz) combined with moderate discharge gaps (≤3.5 mm) or ii) high pulse frequencies (>20 kHz) combined with high discharge gaps (>3.5 mm). Further, the electrode configuration itself significantly affects the reactor performance. When applying same operating conditions, the plate-to-plate configuration attains lower olefin (C2) yield than the co-axial one (~27% vs ~34%, respectively) since lesser energetic discharges are ignited (11 W vs 17 W), but ~20% lower energy is used due to lower electric energy dissipation into gas heating. The plate-to-plate configuration also features significantly higher performance stability and robustness in carbon formation, enabling an order-of-magnitude longer operating periods.

Effect of Phosphorus Modification of Zeolites Y and ZSM-5 on the Cracking of Hydrotreated Vacuum Gas Oil and a Vacuum Gas Oil–Sunflower Oil Mixture

The effect of the preliminary impregnation of zeolites HREY and HZSM-5 with ammonium phosphate before introducing them into the composition of dual-zeolite catalysts has been studied. It has been found that the modification leads to a change in the main textural characteristics of the zeolites. Both the specific surface area and the meso- and micropore volume of the zeolites decrease. The total acidity of HREY and HZSM-5 and the number of strong acid sites in them also decrease. Tests on the conversion of hydrotreated vacuum gas oil and a vacuum gas oil–sunflower oil mixture under catalytic cracking conditions have shown that the modification of the zeolites leads to an increase in the total yield of the propane–propylene and butane–butylene fractions with a high olefin content in them, even with a decrease in the feedstock conversion.

Synthesis of gallium-containing ZSM-5 zeolites by the seed-induced method and catalytic performance of GaZSM-5 and AlZSM-5 during the conversion of methanol to olefins

Abstract Ga isomorphically substituted HZSM-5 and AlZSM-5 with different Si/Ga and Si/Al ratios were synthesized by a seed-induced hydrothermal in situ synthesis. This strategy significantly reduced organic templates in the synthesis process. Various techniques, including XRD, SEM, TEM, XRF, NMR, N2-sorption and H2-TPR, were used in the analogy of the Ga-containing ZSM-5 zeolites and AlZSM-5. The acidities were evaluated by NH3-TPD, Py-IR and acetonitrile-TPD in detail. The Bronsted acidity of GaZSM-5 was introduced by the framework incorporation of Ga atom, which led to a lower intrinsic acid strength than incorporation of Al atom. The effect of gallium incorporation into the MFI zeolite on the catalytic lifetime and the product distribution in methanol-to-olefins (MTO) was also investigated. GaZSM-5 showed a higher amount of Lewis acid sites than did AlZSM-5. More strong acid sites, Bronsted acid sites and a higher B/L ratio have been observed for the AlZSM-5 sample, which is related to the high olefin selectivity of AlZSM-5. ZSM-5 showed higher selectivity of C2H4 and C3H6 than GaZSM-5 samples at reaction temperature of 320 °C, a space velocity of 20 h−1 and reaction time of 8 h. The selectivity of C2H4 and C3H6 over the ZSM-5 samples reached 57%.

The dating of petroleum fluid residence time in subsurface reservoirs. Part 1: A radiolysis-based geochemical toolbox

The radiometric dating of geological events was a crucial achievement leading to the establishment of the geological time scale. The dating of the timing of petroleum charge into, and the determination of petroleum residence times in a geological trap would also be significant, as it would remove ubiquitous speculation concerning the history of reservoir charging in any basin setting. A thorough review of prior strategies to estimate the residence time of petroleum fluids in subsurface reservoirs revealed that few if any methods currently used provide useful estimates of the residence age of fluids. This paper is focused on the age dating of petroleum residence time in reservoirs based on the compositional alterations of reservoired fluids caused by natural radiation. This preliminary paper sets out the geochemical landscape and constraints on radiation-based age dating proxies. We report results on the propagation of radiation through reservoir rocks, which indicate that gamma radiolysis is a primary route to crude oil alteration. Gamma ray radiolysis experiments on crude oils at both natural and elevated radiation doses have been completed and the changing crude oil composition observed using LC, GC-MS and NMR. Reservoir fluids are naturally immersed in radioactive subsurface media that cause systematic alteration to crude oil composition with time, but the chemical changes are small in most natural settings. The degree of radiolysis of individual petroleum compounds was found to depend on chemical class, molecular size, initial compound concentration and the nature of the oil matrix, indicating that a proxy system for dating of petroleum charge times and oil residence times in petroleum traps will likely depend on case-specific calibrations. We define the apparent gamma ray radiolysis susceptibility (kGy−1) of different compounds. Large alkanes, such as high molecular weight normal alkanes (>C22) or hopanes, have high radiolysis susceptibility and show the most rapid decrease in component concentration with increasing radiation dose. In contrast, condensed aromatic hydrocarbons and diamondoid hydrocarbons are more resistant to decomposition through radiolysis. While assessing the decrease in concentration of a compound through radiolysis is a practical objective, it is more difficult to assess the production of new, unique radiolysis products given the great diversity and low concentrations of individual compounds produced. However, monitoring the production of specific functional groups during radiolysis of crude oils, using NMR spectroscopy, was found to be a feasible proxy analytical target. Analysis of newly generated carbon-carbon double bonds in bulk crude oils may represent an optimal approach for development as a radiolysis proxy. We propose a route to assessing in-reservoir crude oil radiation dose.

Key Features of Cotransformation of Vacuum Gas Oils and Vegetable Oils on Dual-Zeolite Cracking Catalysts

The study of cotransformation of petroleum fractions with vegetable oils on dual-zeolite cracking catalysts has revealed that vegetable oils differing in fatty acid composition admixed to vacuum gas oil, characterized by a high aromatics content, facilitate the conversion and increase the yields of the gasoline fraction and light olefins. In the case of vacuum gas oil cocracking with a vegetable oil having a high unsaturation index (sunflower oil), the oil content in the mixture should not exceed 5 wt %, since its higher content in the mixture leads to enhanced coking of the dual-zeolite catalyst and simultaneous reduction in the yield of the desired cracking products. The effect of preliminary impregnation of HREEY and HZSM-5 zeolites with ammonium hydrogen phosphate before their incorporation into the composition of dual-zeolite catalysts has been investigated as well. It has been found that the modification results in a decrease in the total acidity of zeolites. In the cracking of a mixture of vacuum gas oil and sunflower oil, it has been determined that the modification of zeolites leads to an increase in the total yield of the propane–propylene and butane–butylene fractions with high olefin content. Keywords: vacuum gas oil, vegetable oils, dual-zeolite catalyst, gasoline fraction

Engineering the Catalytic Properties of HZSM5 by Cobalt Modification and Post-synthetic Hierarchical Porosity Development

Hierarchical zeolites have been identified as special catalytic materials with improved catalytic properties. In this study, hierarchical bifunctional ZSM5 based catalysts were prepared by desilication for controlled mesoporosity development and have been modified by Co doping. Their performance in the catalytic pyrolysis of oak in a lab scale reactor was evaluated. Desilicated counterparts were proven more active in deoxygenation of bio oil, while carbon deposition on the catalysts reduced compared to non-desilicated counterparts. Increased Lewis acidity favors decarboxylation reactions, while higher olefins as well as PAH content indicate easier diffusion within and from the porous network and interactions in the mesopores. The conversion of bulky lignin molecules (alkoxy phenols) is enhanced by the mesopores, while acidity is of secondary importance. Coke deposition inside the pores is more profound in the desilicated catalysts due to larger pore size. Carbon deposition on the catalysts is reduced in the following order: HZSM5 > Co/HZSM5 > Ds-HZSM5 > Co/Ds-HZSM5. GC–MS characterization of the CH2Cl2 soluble coke indicated that for the desilicated counterparts the main coke precursors are the bulky lignin molecules which are partially deoxygenated.

Macroporous scaffolds of cross-linked Poly(ɛ-caprolactone) via high internal phase emulsion templating

A high internal phase emulsion based ring-opening polymerization (HIPE-ROP) of ɛ-caprolactone (CL) was conducted to fabricate macroporous scaffold in a single-step. An oil-in-oil HIPE of CL was formed using high molecular weight olefin (C10-C16) dispersed in continuous medium comprised of CL, a bifunctional cross-linking monomer bis-ɛ-caprolactone-4-yl (BCY) and catalyst stannous octoate (Sn(Oct)2). The emulsion was stabilized using nonionic surfactant, pluronic F127 and polymerization was conducted at 120 °C without any inert atmosphere for a period of 8 h. Complete monomer conversion and cross-linking was achieved and am acroporous scaffold of desired shape was obtained, having in-situ generated porosity and interconnected pores. All chemicals were purposely used without any purification and the high temperature process prevented deactivation of catalyst. The HIPE-ROP developed in this way was found to be highly feasible for conducting otherwise moisture sensitive organo-metallic catalyst based ROP. The morphology of HIPE was directly transferred to macroporous structure of the scaffold in this process where pore size was reproducibly controlled by variation in volume fraction of dispersed phase and cross-link density. The resultant macroporous scaffold showed superior compressive loading and swelling capacity. The porous scaffolds also exhibited excellent osteoblast (MG63) attachment and proliferation. HIPE-ROP based macroporous scaffold of cross-linked PCL thus developed paved a new route to create porous scaffolds of aliphatic polyesters in a single step. The method also reflected high commercial viability by potential conversion into a continuous process.

Impacts of activated carbon amendments, added from the start or after five months, on the microbiology and outcomes of crude oil bioremediation in soil

The use of activated carbon (AC) amendments to reduce exposure risks for hydrophobic contaminants like polycyclic aromatic hydrocarbons (PAHs) by adsorption is an innovative soil remediation approach. However, AC amendment side-effects on the pollution biodegradation are poorly understood. This study assessed for optimized nutrient ratio conditions, effects of 5% soil wet weight AC amendments, if added from the beginning or after five months, on the outcomes of one year of crude oil polluted soil bioremediation. CO2, residual hydrocarbon concentrations and microbial community structure analysis revealed how AC amendment hindered crude oil biodegradation much more, if added from the start, as compared to after 5 months, i.e. after the initial phase of biodegradation. Putative crude oil degrading microorganisms from the genera Marinobacter, Parvibaculum, Salinibacterium, Muricauda, and Alcanivorax were more sensitive to the AC amendment than those from the genus Rhodococcus. Rhodococci possess hydrophobic cell walls which may enable them to accumulate hydrocarbons in the AC amended soil, despite of their reduced availability. AC amendment from the start had the highest alkane and total US EPA PAH residues, but was more effective than one year of bioremediation, with or without AC amendment after 5 months, in reducing PAH availability in the soil.