Fixed-bed Down-flow Reactor Research Articles

Sorption-enhanced glycerol steam reforming over lithium cuprate-based bifunctional material for the production of high-purity hydrogen

We investigated the production of high-purity H2 through sorption-enhanced glycerol steam reforming (SEGSR) using lab-made bifunctional materials consisting of nickel, Al2O3, and Li2CuO2. Different bifunctional materials were prepared with 10 wt % Ni loading but varying wt % of Al2O3 and Li2CuO2, and their catalytic activity was evaluated in a continuous fixed-bed down-flow reactor. HM-50, which had an equal wt % of Al2O3 and Li2CuO2, showed the highest performance. The conversion of glycerol and the purity of H2 were examined with respect to temperature, feed flow rate, and steam-to-carbon molar ratio (S/C). At the optimum reaction conditions (temperature = 700 °C, feed flow rate = 0.5 ml/min, and S/C = 6), glycerol conversion and H2 purity were 100 % and 94 mol %, respectively. The adsorption capacity of HM-50 was found to be 3.9 mmol CO2 per gram. With a breakthrough time of 15 min, the substance was stable for 13 adsorption-desorption cycles. The material was regenerated by substituting the feed with a N2 and steam mixture heated to 700 °C for 30 min. A most likely reaction mechanism suggested that glycerol was catalytically converted to acetaldehyde, which was then quickly decomposed to CO and CH4. We are the first research team to investigate the use of Li2CuO2 in any steam reforming process.

One-Step Conversion of n-Butanol to Aromatics-free Gasoline over the HZSM-5 Catalyst: Effect of Pressure, Catalyst Deactivation, and Fuel Properties as a Gasoline.

Sustainable production of gasoline-range hydrocarbon fuels from biomass is critical in evading the upgradation of combustion engine infrastructures. The present work focuses on the selective transformation of n-butanol to gasoline-range hydrocarbons free from aromatics in a single step. Conversion of n-butanol was carried out in a down-flow fixed-bed reactor with the capability to operate at high pressures using the HZSM-5 catalyst. The selective transformation of n-butanol was carried out for a wide range of temperatures (523-563 K), pressures (1-40 bar), and weight hourly space velocities (0.75-14.96 h-1) to obtain the optimum operating conditions for the maximum yields of gasoline range (C5-C12) hydrocarbons. A C5-C12 hydrocarbons selectivity of ∼80% was achieved, with ∼11% and 9% selectivity to C3-C4 paraffin and C3-C4 olefins, respectively, under optimum operating conditions of 543 K, 0.75 h-1, and 20 bar. The hydrocarbon (C5-C12) product mixture was free from aromatics and primarily olefinic in nature. The distribution of these C5-C12 hydrocarbons depends strongly on the reaction pressure, temperature, and WHSV. These olefins were further hydrogenated to paraffins using a Ni/SiO2 catalyst. The fuel properties and distillation characteristics of virgin and hydrogenated hydrocarbons were evaluated and compared with those of gasoline to understand their suitability as a transportation fuel in an unmodified combustion engine. The present work further delineates the catalyst stability study for a long time-on-stream (TOS) and extensive characterization of spent catalysts to understand the nature of catalyst deactivation.

Optimal mixing method of ZnZrOx and MOR-type zeolite to prepare a bifunctional catalyst for CO2 hydrogenation to lower olefins

In recent years, the issue of global warming caused by CO2 emissions has become a critical problem and poses a worldwide challenge. To address this issue, we have developed a bifunctional catalyst that can convert CO2 to lower olefins in a single stage. Our bifunctional catalysts are a combination of two catalysts, a CO2-to-methanol hydrogenation catalyst (Zn-doped ZrO2, named ZnZrOx) and a methanol-to-olefin catalyst (MOR-type zeolite, named MOR104). In this research, we examined the impact of various mixing modes of the two catalysts on product distribution. We tested four different mixing modes using a down-flow fixed bed reactor: (a) ZnZrOx in the upper layer and MOR104 in the lower layer, (b) catalysts were mixed randomly after being pelletized separately, (c) MOR104 in the upper layer and ZnZrOx in the lower layer, and (d) granulated catalyst produced by physically mixing both catalyst powders. Our findings indicated that the best performance was achieved with catalyst (d), where the two catalysts were mixed in close proximity. This proximity resulted in efficient supply of methanol produced on ZnZrOx to MOR104. In other words, the MTO reaction in MOR104 efficiently consumed methanol molecules produced via equilibrium-limited CO2-to-methanol hydrogenation. When ZnZrOx and MOR104 were thoroughly mixed, the conversion of CO2 to methanol shifted towards the product side, resulting in a greater overall utilization of CO2. Furthermore, the bifunctional catalyst we developed was stable for six hours. Since there have been few studies of bifunctional catalysts containing zeolites other than ZSM-5 and SAPO-34, this study opens up new opportunities for bifunctional catalysts specialized for one-pass hydrocarbon synthesis through CO2 hydrogenation.

Moderate pressure boosts the aromatization activity of HZSM-5 zeolite during catalytic pyrolysis of lignocellulosic materials

Lignocellulose pyrolysis has been deeply investigated in the past years as a potential route for the production of advanced biofuels and biochemicals from residues and wastes. However, the effect of pressure has rarely been addressed in catalytic pyrolysis processes. Accordingly, the current work reports a comprehensive study on the pressure influence during the catalytic pyrolysis of different lignocellulosic materials (oak wood, cellulose, hemicellulose, and lignin) using nanocrystalline HZSM-5 zeolite as a catalyst and a downflow fixed-bed reactor. In thermal pyrolysis tests, pressure increase affects negatively the bio-oil* (organic components in the liquid products) since it reduces its yield in favor of the production of char and gases. However, in the case of the catalytic pyrolysis tests, working under moderate pressure (10 bar) has very positive effects on bio-oil upgrading, minimizing its oxygen concentration (< 10 wt.%) and sharply increasing the carbon yield of aromatic hydrocarbons, while the undesirable coke deposited on the catalyst surface can be even reduced. This finding denotes the occurrence of a remarkable synergistic effect between the pyrolysis pressure and the catalyst loading. These outstanding results are attributed to a more efficient activity of the zeolite under mild pressurization since both oxygenated species and light olefins are more strongly adsorbed over the catalyst surface, facilitating their subsequent transformation into aromatic hydrocarbons. The sharp enhancement of the deoxygenation and aromatization activity does not involve higher coke deposition over the zeolite surface, thus attenuating one of the major limitations of the lignocellulose catalytic pyrolysis process.

Upgradation of Eugenol to ASTM D 1655 standard Bio-Jet(A) fuel range hydrocarbons via hydrodeoxygenation process over Ru-Ni supported KIT-6/HZSM-5

A novel hierarchical Zeolite composite was successfully synthesized for bio-fuel application via catalytic hydrodeoxygenation of Lignin-Derived Phenolic Model Compound (LDPMC) in a downflow fixed bed reactor. The utilization of massive noble metals in the hydrodeoxygenation process in factories leads to an increase in the total cost of LDPMC technology. A fractional replacement of Ruthenium (Ru) by another transition metal Nickel (Ni), is a potentially effective method. The core asset of the novel synthesized catalyst displayed the advantageous properties of both micro- and mesoporous. This could be confirmed by the results of XRD, BET, and surface analyzing microscopes. The synthesis of Rux-Ni10-x/KIT-6-HZSM-5 (x = 2, 4 & 6) bimetallic-monometallic catalysts and their catalytic performance for hydrodeoxygenation of Eugenol are reported in the present study. The hierarchical Zeolite composite catalysts were synthesized by a wet-chemistry method. The active catalysts were characterized by ATR-IR, H2-TPR, NH3-TPD, HR-SEM, HR-TEM, XPS, and TGA techniques. The synthesized 2 %Ru-8 %Ni/KIT-6-HZSM-5 exhibited 100 % conversion with a maximum yield of 48.70 % of the complete deoxygenated product (Jet A range fuel) due to the synergistic effect between Ru and Ni on hierarchical Zeolite composite support and superior catalytic activity compared to the other synthesized catalysts with the highest metal dispersion. The stability and reproducibility of catalysts were steady even after 4 cycles. The Ruthenium and Nickel loaded hierarchical Zeolite composite support showed superior activity related to other reported catalysts even at atmospheric pressure under variable experimental conditions.

Synthesis of Oxygenated Hydrocarbons from Ethanol over Sulfided KCoMo-Based Catalysts: Influence of Novel Fiber- and Powder-Activated Carbon Supports

Ethanol has become a viable feedstock for basic organic synthesis. The catalytic conversion of ethanol provides access to such chemicals as diethyl ether, ethyl acetate, and acetaldehyde. Carbonaceous materials are extensively studied as supports for heterogeneous catalysts due to their chemical and thermal stability, high surface area, and tunable texture. In this paper, ethanol conversion over K10Co3.7Mo12S-catalysts supported on novel activated carbon (AC) materials (i.e., novel powder-AC (DAS and YPK-1), fiber non-woven AC material (AHM), and fabric active sorption (TCA)) was investigated. The catalysts were prepared by the incipient wetness co-impregnation method followed by sulfidation. The catalysts were characterized by employing N2 adsorption–desorption measurements, TEM, SEM/EDX, UV–Vis spectroscopy, and XRF. Catalytic performance was assessed in a fixed-bed down-flow reactor operating at 320 °C, 2.5 MPa, and with continuous ethanol feeding in an He atmosphere. Activity is highly dependent on the support type and catalyst’s textural properties. The activity of the fiber-supported catalysts was found to be greater than the powder-supported catalysts. Ethanol conversion at T = 320 °C, P = 2.5 MPa, and GHSV = 760 L h−1 kgcat−1 increased as follows: (38.7%) KCoMoS2/YPK-1 &lt; (49.5%) KCoMoS2/DAS &lt; (58.2%) KCoMoS2/TCA &lt; (67.1%) KCoMoS2/AHM. Catalysts supported by powder-AC enhanced the formation of MoS2-crystallites, whereas the high acidity of fiber-AC seemed to inhibit the formation of MoS2-crystallites. Simultaneously, a high surface area and a microporous catalytic structure enhance the formation of oxygenates from hydrocarbons. The dehydration and dehydrogenation reactions, which led to the creation of ethene and acetaldehyde, were shown to require a highly acidic catalyst, while the synthesis of ethyl acetate and higher alcohols required a less acidic catalyst.

Experimental Determination on the Deactivation Kinetics of Residue Hydroprocessing in a Two-Stage Fixed Bed Loaded with HDM and HDS Catalysts

Residue catalytic hydrogenation was carried out in a two-stage downflow fixed-bed reactor system, with a HDM catalyst in the first stage and HDS catalyst in the second one, to mimic the industrial operation. The experiments were run at five sets of temperatures (395 °C (first reactor)/405 °C (second reactor), 400 °C/410 °C, 405 °C/415 °C, 410 °C/420 °C, and 420 °C/430 °C). It was found that the initial stage deactivation was mainly caused by the rapid deposition of coke. Gradually, the deposition of metal sulfides leads to a slow deactivation in the middle stage of operation. A deactivation model that considers the catalyst activity as a function of TOS was proposed and applied to the hydrotreating reaction. The deactivation parameters of HDCCR, HDS, HDNi, and HDV in the two reactors were obtained by fitting the experimental data at the outlet of the two reactors. According to the deactivation curves of catalysts, it is proposed that the deactivation of HDM catalyst is faster than that of HDS catalyst, and multi-bed hydrogenation can effectively increase the catalyst life.

Preparation of NiOx/SiO2–Al2O3 catalysts by a homogenous precipitation method and their catalytic activity for ethylene oligomerization

NiOx/SiO2–Al2O3 catalysts with different pore structures (BET specific surface area: 303–709 m2 g−1, average pore size: 2.2–5.1 nm), acid properties (total amount of acid sites: 0.99–1.66 mmol g−1), and NiO particle sizes (4.6–14.7 nm) were prepared, and the structural factors influencing their catalytic activity for ethylene oligomerization were studied. SiO2–Al2O3 support was prepared by means of a homogeneous precipitation method, and supports with different physicochemical properties were obtained by changing the preparation conditions. Ni was loaded by means of an impregnation method. Catalytic reactions were performed in a fixed-bed down-flow reactor operated at 300 °C and 0.1 MPa. NiOx/SiO2–Al2O3 catalysts prepared with the homogenous precipitation method had a higher surface area, more uniform pore size, and a larger amount of acid sites, and they showed a higher activity not only compared with NiOx/SiO2–Al2O3 catalysts prepared by means of our previous coprecipitation method but also compared with Ni-AlSBA-15, the best heterogenous catalyst for ethylene oligomerization reported to data. The catalytic activities of the NiOx/SiO2–Al2O3 catalysts strongly depended on the BET specific surface area and the amounts of acid sites. The optimal amounts of weak, medium-strength, strong, and total acid sites were 0.5, 0.3, 0.4, and 1.2 mmol g−1, respectively. Examination of the structure–activity relationships of the catalysts suggested that their catalytic activity was promoted by close contact between the Ni and acid sites.

Utilisation of a basic K-grafted USY zeolite in catalytic pyrolysis of wheat straw to produce valuable oxygenated compounds

The catalytic properties of K-grafted USY zeolite in fast pyrolysis of acid-washed wheat straw have been investigated using the parent USY sample as a reference. Potassium was incorporated into the zeolite by replacing H+ protons from framework hydroxyl groups with K+ cations. CO2-TPD confirmed the presence of basic sites, with mainly weak-mild strength, in the resulting material. Catalytic tests were performed in a down-flow fixed bed reactor with two furnaces. The thermal zone operated at 550 °C, whereas the temperature of the catalytic bed was varied from 400 to 500 °C. The catalysts were tested at two different catalyst to biomass ratios (C/B = 0.2 and 0.6). The K-USY sample was quite more active in bio-oil* (bio-oil in a water-free basis) conversion and upgrading than the parent zeolite, as denoted by the increased production of gases and the lower oxygen content of the organic liquid phase, although it also suffered higher coke deposition. Sharp changes were observed in the bio-oil* composition when using the K-USY catalyst. In particular, the presence in this material of a high population of weak-mild basic sites favoured the conversion of lignin oligomers and the occurrence of ketone-forming reactions from holocellulose. As a result, phenols and ketones were the main components (with an overall concentration up to 31.5 wt%) in the bio-oil* obtained over K-USY, which is an interesting result due to their potential use for the preparation of fine chemicals with high-added value.

Enhancing the CO2 methanation activity of γ-Al2O3 supported mono- and bi-metallic catalysts prepared by glycerol assisted impregnation

Conventional Ni/Al2O3 catalyst, currently used for COx removal in ammonia production, admits room for improvement as catalysts for application in low temperature CO2 methanation, which is the aim of this work. The Incipient Wetness Impregnation (IWI) has been replaced by Glycerol Assisted Impregnation (GAI) method and, afterwards, a secondary metal (Ru) has been co-impregnated forming a bimetallic system. The monometallic as well as bimetallic systems have been characterized by several techniques (TGA, XRD, N2-physisorption, TEM, H2-TPR, H2-TPD, STEM-EDX and operando FTIR) and tested for CO2 methanation reaction in a downflow fixed bed reactor (conditions: P =1 bar, H2: CO2 ratio = 4 and WHSV = 30,000 mL h−1 g−1). GAI method together with a reducing calcination atmosphere (20 %H2/N2) results effective to avoid the formation of large metal particles during the synthesis, especially for Ru/Al2O3 formulation. In fact, the Ru dispersion of the catalyst prepared by GAI (RuAlGAI) is around 5 times higher than that of RuAlIWI catalyst. On the other hand, NiAlGAI presents larger population of reduced particles but bigger in size than NiAlIWI catalyst, which finally provides the former with slightly higher metal surface and superior catalytic performance. By co-impregnating small amounts of Ru (0.5, 1.0 or 1.5 wt%) the Ni surface is considerably increased which, together with Ru synergistic collaboration, results in a methane yield rise from 20 to 44 % at 300 °C. The operando FTIR results show no differences in the reaction pathway with GAI preparation method and incorporation of Ru, but different evolution of reaction intermediates concentration with temperature. The bimetallic Ni-RuAl system presents much higher capacity to adsorb CO and hydrogenate the reaction intermediates (adsorbed formates and carbonyls) by dissociated H2 than its monometallic counterparts.

The Synthesis of YNU-5 Zeolite and Its Application to the Catalysis in the Dimethyl Ether-to-Olefin Reaction.

During prior investigations of the synthesis of the novel zeolite YNU-5 (YFI), it was found that a very slight amount of an impurity phase contaminated the desired zeolitic phase. This impurity was very often ZSM-5 (MFI). The phase composition was determined to be sensitive to the water in the synthesis mixture, and it was possible to obtain a pure phase and also to intentionally generate a specific impurity phase. In the present work, trials based on the dimethyl ether-to-olefin (DTO) reaction using a fixed-bed downflow reactor were performed to assess the effect of the purity of YNU-5 on its catalytic performance. Dealuminated pure YNU-5 exhibited rapid deactivation due to coking at time on stream (TOS) values exceeding 5 min. Surprisingly, this deactivation was greatly suppressed when the material contained a trace amount of ZSM-5 consisting of nano-sized particles. The formation of ZSM-5 nanoparticles evidently improved the performance of the catalytic system during the DTO reaction. The product distributions obtained from this reaction using highly dealuminated and very pure YNU-5 resembled those generated by 12-ring rather than 8-ring zeolite catalysts. The high selectivity for desirable C3 and C4 olefins during the DTO reaction over YNU-5 is beneficial.

Co-Gasification of Crude Glycerol/Animal Fat Mixtures

The aim of this work was to assess the technical viability of glycerol/fat co-gasification. The gasification performance was studied in a downflow fixed bed reactor using activated alumina particles as bed material and steam as oxidizing agent. The effect of gasification temperature, from 800 to 950 °C was studied with a feed mixture with 10% (w/w) of animal fat. The influence of fat incorporation on the feedstock in the overall gasification process was also performed, using 3% (w/w) and 5% (w/w) of fat in feed mixtures. Samples of dry gas from the gasifier were collected and analyzed by gas chromatography in order to determine the CO, CO2, CH4, and H2 content. The best results were obtained using the highest tested temperature, 950 °C, and using 3% (w/w) of animal fat in the feed mixture. The overall results revealed that the co-gasification of glycerol/animal fat mixtures seems to be a feasible technical option.

Synthesis and Application of Novel NiMoK/TS-1 for Selective Conversion of Fatty Acid Methyl Esters/Triglycerides to Olefins.

Methyl palmitate (or triglyceride) was converted into C15 olefin with remarkable selectivity using nickel–molybdenum oxides on the mesoporous titanosilicate support. The olefin has one carbon atom less than the acid portion of the ester. A new catalyst NiMoK/TS-1 was synthesized in which the effect of acidity of supports and molybdenum loading on the decarboxylation conversion along with product selectivity was investigated in methyl palmitate conversion into C15 olefin. The prepared catalysts were analyzed using ammonia-temperature-programmed desorption (NH3-TPD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) techniques. The reaction was carried out using a vapor-phase fixed-bed downflow reactor system at atmospheric pressure. The NiMoK/TS-1 catalyst at a weight hourly space velocity (WHSV) of 5.6/h was found to be selective toward C15 olefin. The catalyst was stable up to 15 h, and it can be regenerated with no considerable decrease in the activity even after fourth reuse. Beyond 653 K, the conversion of methyl palmitate increased but the selectivity for C15 products and C15 olefin was decreased.

Co-gasification of glycerol/fat mixtures in a downflow fixed bed reactor: Preliminary results

The aim of this work was to assess the technical viability of glycerol/fat co-gasification. The gasification performance was studied in a downflow fixed bed reactor using steam as oxidizing agent. Tests were performed with a mixture of 10% of fat and 52% of water, and the effect of temperature was evaluated in the 800 ºC to 950 ºC range. Samples of dry gas from the gasifier were collected and analysed by gas chromatography in order to determine the CO, CO2, CH4 and H2 content. The results revealed that the co-gasification of glycerol/fat mixtures seems to be a feasible technical option. Best results of the gasification parameters were obtained at the highest tested temperature, 950 °C.

Molecular-size selective hydroconversion of FCC light cycle oil into petrochemical light aromatic hydrocarbons

Abstract The catalytic hydroconversion of light cycle oil (LCO) from a fluid catalytic cracking (FCC) unit into petrochemical light aromatics was conducted in a fixed-bed down-flow reactor under 6 MPa. A hydrocracking (HDC) study was conducted using pre-hydrotreated LCO (HDT-LCO). Due to the wide molecular size distribution of the aromatic compounds in LCO, which range from mono- to tri+-ring aromatics, a combination of H-ZSM-5 (Z), H-Beta (B) and mesoporous H-Y(Y) zeolite was employed as zeolite supports for the HDC catalysts. The Mo-S/BYZ catalyst was found to achieve higher yield of light aromatics and higher conversion of large molecular-size C11+ heavy aromatics than those for Mo-S/BZ without mesoporous H-Y in the HDC of HDT-LCO. Although the Mo-S/ H-Y catalyst itself did not show selectivity toward light aromatics in the HDC of tetralin, the incorporation of a small fraction of mesoporous H-Y in the HDC catalyst promoted the cracking of large molecular-size C11+ heavy aromatics into light aromatics including benzene, toluene and xylene (BTX). The Mo-S/BYZ catalyst also exhibited an excellent stability over more than 100 h. Hence, the Mo-S/BYZ catalyst, which produced a high yield of BTX-rich light aromatics and demonstrated excellent catalyst stability, represents a promising HDC catalyst for LCO upgrading.

Selective hydrotreating and hydrocracking of FCC light cycle oil into high-value light aromatic hydrocarbons

Comprehensive series tests on hydrotreating (HDT) and hydrocracking (HDC) of fluid catalytic cracking (FCC) light cycle oil (LCO) into high-value light aromatics rich in benzene, toluene, and xylenes (BTX) were conducted in a fixed-bed down-flow reactor under medium pressure (6 MPa). Two different LCOs, LCO-1 (a full-range LCO) and LCO-2 (340 °C− LCO which contained a smaller fraction of refractory alkyl(C2+)-carbazoles and heavy tri+-aromatics (three and more rings aromatics) than LCO-1), were used as feedstocks. Comparison of NiW-S, NiMo-S, and CoMo-S supported on γ-Al2O3 and a commercial catalyst (for vacuum gasoil hydrodesulfurization) as LCO HDT catalysts revealed that NiMo-S/γ-Al2O3 allowed for highly selective hydrogenation (HYD) of di+-aromatics (two and more rings aromatics) into mono-aromatics with minimal loss of aromatics at high HDN conversion rates. For HDC catalysts, NiMo-S, CoMo-S, and Mo-S were supported on a hybrid zeolite, BZ(x) (a mixture of H-Beta (B) and H-ZSM-5 (Z) (x wt%)). Since Mo-S exhibited moderate HYD power and H-ZSM-5 promoted the dealkylation of alkyl-aromatics into BTX, Mo-S/BZ(10) yielded the largest amount of BTX in the HDC model of tetralin among the three catalyst analyzed. The HDC of hydrotreated LCO-1 (HDT-LCO-1) over Mo-S/BZ(10) catalyst generated a low yield of BTX-rich light aromatics because of the limited conversion of C11+ heavy aromatics. However, during the HDC of HDT-LCO-2, the yield of BTX-rich light aromatics was close to the theoretical yield (48.4 wt%) over a wide temperature range when Mo-S/BZ(10) was used as catalyst, which indicated the highly selective HDC behavior of Mo-S/BZ(10) for this reaction. Therefore, NiMo-S/γ-Al2O3 and Mo-S/BZ(10), which exhibited well-balanced metallic and/or acidic functions, were promising HDT and HDC catalysts, respectively, for the selective conversion of LCOs into high-value BTX-rich light aromatics at high yields.

Adsorptive hydrogen chloride and combined hydrogen chloride–hydrogen sulphide removal from biogas for solid oxide fuel cell application

In order to reduce the toxic effect on solid oxide fuel cells performance caused by biogas contaminated with hydrogen chloride and hydrogen sulphide, the purification of biogas is essential. Adsorptive gas purification is a highly auspicious technology to provide pollution-free biogas for solid oxide fuel cell-based power units. In this work the authors examined the influence of different parameters onto the adsorption capacity of three commercially available sorbents. Experimental runs in a laboratory glass downflow fixed-bed reactor were carried out to analyse the adsorption capacity of a potassium carbonate impregnated activated carbon and two sorbents based on a mixture of aluminium oxide and silicon dioxide. Hydrogen chloride removal was accomplished with the impregnated activated carbon and metal oxide-based sorbents. Hydrogen chloride adsorption capacity was analysed under space velocities 8000 and 16,000 h−1. In addition, the effect of a hydrogen chloride inlet concentration of 100 and 1000 ppmv was investigated. Furthermore, pellets in the size of 3–4 mm in diameter were crushed into a fraction between 500 and 1000 µm to investigate the influence of particle size on hydrogen chloride adsorption capacity. Additionally, the combined adsorption of hydrogen chloride and hydrogen sulphide was realized using the impregnated activated carbon. The experimental runs and the results obtained in this work provide useful data for designing an adsorption reactor to clean up biogas and optimizing the process.

Hydrodeoxygenation of triglycerides over reduced mesostructured Ni/γ-alumina catalysts prepared via one-pot sol-gel route for green diesel production

Environmentally friendly non-sulfided mesostructured Ni/γ-alumina catalysts were synthesized and developed to produce green diesel from canola oil. The catalysts were prepared either by a one-pot sol-gel (SG) via evaporation-induced self-assembly (EISA) or by incipient wetness impregnation (IMP). They were characterized by N2 adsorption-desorption, XRD, XPS, NH3-TPD and TEM. Due to the incorporation of nickel in the mesostructured framework, bulk nickel oxide species are lower for SG catalysts compared to IMP ones. Formation of active metallic nickel was confirmed after in-situ pre-reduction in H2 for both SG and IMP catalysts. Continuous hydrotreatment of canola oil was performed in a down-flow fixed-bed reactor, and the liquid hydrocarbon products mainly contained C15-C18 n-alkanes. SG catalyst exhibited a better stability up to 10 h of time on stream (TOS). The IMP catalyst initially showed higher conversion than SG up to TOS:300 min; it thereafter decreased sharply to values lower than those of SG.

Design of selective hydrocracking catalysts for BTX production from diesel-boiling-range polycyclic aromatic hydrocarbons

Various metallic components (Ni, NiSn, NiW-S, CoMo-S and NiMo-S) with different hydrogenation (HYD) activities were supported on H-Beta or hybrid zeolites (BZ(x), where x denotes the weight percentage of H-ZSM-5 in the physical mixture of H-Beta and H-ZSM-5). These bifunctional catalysts were applied to the hydrocracking (HYC) of tetralin in a fixed-bed down-flow reactor at 4MPa as a model reaction for polycyclic aromatic hydrocarbon (PAH) conversion to high-value benzene, toluene, and xylenes (BTX). From the HYC of tetralin over the series of metals/H-Beta catalysts, it was found that CoMo-S/H-Beta and NiMo-S/H-Beta, whose metallic components show moderate activities in the HYD of tetralin, exhibit higher BTX yields than the other catalysts whose metals have excessively high or low HYD activities. However, these catalysts show limited BTX yield (∼47.3wt% at 425°C) owing to the large coproduction of alkylbenzenes other than BTX. When metals with moderate HYD activities are supported on the hybrid zeolites, the BTX yield is significantly enhanced by the effect of H-ZSM-5 in the dealkylation of alkylbenzenes into BTX. NiMo-S/BZ(10) provides a BTX yield of 54.3wt% and a total 1-ring aromatic yield as high as 63.8wt% (corresponding to 94.4% of the theoretical maximum of 67.6wt%) at 425°C. Therefore, the NiMo-S/BZ(10) catalyst, where the metallic and acidic functions and structural properties of the zeolite are well balanced, show promise as an HYC catalyst for the hydroconversion of PAHs into high-value BTX mixtures.

Simultaneous Biodegradation and Detoxification of the Herbicides 2,4-Dichlorophenoxyacetic Acid and 4-Chloro-2-Methylphenoxyacetic Acid in a Continuous Biofilm Reactor

The herbicides 2,4-diclorophenoxiacetic and 4-chloro-2-methylphenoxyacetic acids (2,4-D and MCPA) are widely used in agricultural practices worldwide. Not only are these practices responsible of surface waters contamination, but also agrochemical industries through the discharge of their liquid effluents. In this investigation, the ability of a 2,4-D degrading Delftia sp. strain to degrade the related compound MCPA and a mixture of both herbicides was assessed in batch reactors. The strain was also employed to remove and detoxify both herbicides from a synthetic effluent in a continuous reactor. Batch experiments were conducted in a 2-L aerobic microfermentor, at 28 °C. Continuous experiments were carried out in an aerobic downflow fixed-bed reactor. Bacterial growth was evaluated by the plate count method. Degradation of the compounds was evaluated by UV spectrophotometry, gas chromatography (GC), and chemical oxygen demand (COD). Toxicity was assessed before and after the continuous process by using Lactuca sativa seeds as test organisms. Delftia sp. was able to degrade 100 mg L−1 of MCPA in 52 h. When the biodegradation assay was carried out with a mixture of 100 mg L−1 of each herbicide, the process was accomplished in 56 h. In the continuous reactor, the strain showed high efficiency in the simultaneous removal of 100 mg L−1 of each herbicide. Removals of 99.7, 99.5, and 95.0% were achieved for 2,4-D, MCPA, and COD, respectively. Samples from the influent of the continuous reactor showed high toxicity levels for Lactuca sativa seeds, while toxicity was not detected after the continuous process.