Liquid Hourly Space Velocity Research Articles

JP-8 Desulfurization by CuNa-Y zeolite at elevated temperatures has two distinct stages: Chemisorption followed by surface reactions.

This study evaluates the performance of continuous flow adsorbers for adsorptive desulfurization. JP-8 fuel with 2,230 ppmw of sulfur was treated in a flow-through adsorber packed with CuNa-Y zeolite pellets and operating at 180 °C and 200 psig with liquid hourly space velocities (LHSV) from 0.13 to 3.24 h-1. Our results showed that a flow-through adsorber operating at these conditions can effectively reduce the sulfur content of JP-8 to ultra-low values (1-10 ppmw) over the entire LHSV range tested, although the overall performance of the adsorber declined with increasing flow rates as expected. We also observed that the total sulfur removal exceeded the theoretical adsorption limit of our zeolite adsorbent. Detailed characterization of the treated fuel and spent adsorbent via chromatographic and surface analysis techniques revealed that desulfurization occurs in two stages. Sulfur is initially removed via adsorption (chemisorption) on the CuNa-Y zeolite, an assertion supported by simulations with a transient heterogeneous model. As the adsorbent becomes saturated, however, surface chemical reactions start taking place leading to the formation of hydrogen sulfide and polymerization products, and depositing carbon residue on the zeolite. The spent adsorbent was regenerated by treating it with air at 550 or 600 °C, which restored the adsorption capacity of the material to about 90% of its initial value.

Production of hydro‐processed renewable jet fuel over SAPO ‐11‐based catalyst

The role of single-metal-loaded on SAPO-11-based hydro-processing catalyst to produce renewable jet fuel was investigated in this work. First, three metals, nickel, cobalt, and molybdenum, were selected to be loaded on SAPO-11 separately and their activities were tested over the model feedstock, n-hexadecane. Among the three catalysts, nickel SAPO-11 shows the highest conversion of 70%. Second, the performance of Ni/SAPO-11, synthesized with (Ni/SAPO-11(CA)), and without (Ni/SAPO-11) citric acid was investigated with the hydro-processed alkanes derived from palm oil for the production of hydro-processed renewable jet fuel (HRJ). Catalyst metal particle size, structure, textural properties, acidity, and reduction degree were detected through transmission electron microscope (TEM), X-ray diffraction (XRD), N2 adsorption/desorption, pyridine-adsorbed infrared spectroscopy (Py-IR), and temperature programmed reduction (TPR). The product compositions over the Ni/SAPO-11(CA) catalyst show higher selectivity toward the carbon chain length of jet fuel (C8-C14) for 48% compared to the Ni/SAPO-11. Through the Taguchi method, the optimal operating conditions were found to be: temperature of 380°C, pressure of 52 bar, liquid hourly space velocity of 0.5 h−1, and H2-to-feedstock ratio of 1250, which yielded in 73% conversion to HRJ with 6.1 isomer-to-normal (I-to-N) alkane ratio. The derived cetane number (DCN) and the flash point of HRJ were also obtained to be 56 and 56°C to confirm the compatibility of HRJ with conventional jet fuel.

Steam reforming of acetic acid for hydrogen production over Ni/CaxFeyO catalysts

Three Ni/CaxFeyO (x/y = 2:1, 1:1, 1:2) catalysts are prepared by impregnation method and applied in steam reforming of acetic acid as the model compound of bio-oil for hydrogen production. The effects of reaction temperature, steam to carbon ratio (S/C), liquid hourly space velocity (LHSV) on gas contents and H2 yield are carefully investigated and optimized. The fresh and used catalysts are characterized by BET, XRD, H2-TPR, CO2-TPD, SEM and TG methods. The experimental and characterization results show that the Ni/CaFe2O4 catalyst displays the best activity and stability among the three catalysts, providing 92.1% of H2 yield under S/C = 5, LHSV = 3.4 h−1 and at 600 °C. The strong interaction between Ni and CaFe2O4 support result in the formation of Ni–Fe alloy and Ca2Fe2O5, which shows the synergistic effects on the resistant to carbon deposition and metal sintering, thereby improving the activity and stability of the Ni/CaFe2O4 catalyst.

Bifunctional catalyst of mordenite‐ and alumina‐supported platinum for isobutane hydroisomerization to n‐butane

Abstractn‐Butane has higher value‐added applications than isobutane in the petrochemical process. To improve the catalytic performance of isobutane isomerization catalysts, catalysts of mordenite‐ and alumina‐supported platinum were prepared. The intimacy between metal and acid sites and platinum content was investigated. The effect of reaction conditions on the catalytic performance of the catalyst was analyzed by response surface methodology. The characterization results of X‐ray diffraction (XRD) patterns, specific surface area, and transmission electron microscope (TEM) confirmed high dispersion of platinum on the catalysts. The results of temperature‐programmed desorption of ammonia (NH3‐TPD) indicated that more acid sites existed on millimetre scale and centimetre scale catalysts than on Pt‐HM/Al2O3 and Pt‐Al2O3/HM, which led to low selectivity of n‐butane. The best yield of n‐butane was attained on microscale samples, as the larger diffusion distance inhibited the cracking reaction. The dispersion of reaction products indicated that the increase of platinum content slightly increased the selectivity of n‐butane. Compared with Pt‐HM/Al2O3, Pt‐Al2O3/HM showed high stability due to fewer carbon deposits in the catalytic reaction process. The optimal reaction condition in isobutane isomerization was T = 413.4°C, liquid hourly space velocity (LHSV) = 5.31 h−1, and P = 2.57 MPa.

Advanced Study of Promoted Pt /SAPO-11 Catalyst for Hydroisomerization of the n-Decane Model and Lube Oil

SAPO-11 is synthesized from silicoaluminophosphate in the presence of di-n-propylamine as a template. The results show that the sample obtained has good crystallinity, 396m2/g BET surface area, and 0.35 cm3/g pore volume. The hydroisomerization activity of (0.25)Pt (1)Zr (0.5)W/SAPO-11 catalyst was determined using n-decane and base oil. All hydroisomerization experiments of n-decane were achieved at a fixed bed plug flow reactor at a temperature range of 200-275°C and LHSV 0.5-2h-1. The results show that the n-decane conversion increases with increasing temperature and decreasing LHSV, the maximum conversion of 66.7 % was achieved at temperature 275°C and LHSV of 0.5 h-1. Meanwhile, the same catalyst was used to improve base oil specification by increasing viscosity index and decreasing pour point. The isomerization reaction conditions, employed are temperature (200-300)ºC, the liquid hourly space velocity of 0.5-2h-1, and the pressure kept atmospheric. The present study shows that Pt Zr W/SAPO-11 minimizes the pour point of lubricating oil to -16°C at isomerization temperature of 300°C and LHSV of 0.5 h-1 and viscosity index 134.8.

Insights in the phenomena involved in deactivation of industrial hydrocracking catalysts through an accelerated deactivation protocol

A representative accelerated experimental deactivation procedure was developed to understand the activity loss of bifunctional vacuum gasoil (VGO) hydrocracking catalysts over time. Experiments were performed in an up-flow fixed-bed pilot unit with a typical vacuum gas oil feedstock. The deactivation was measured by tracking the decrease of VGO conversion (370 °C+) with time on stream. The catalyst consisted of nickel-molybdenum sulfide particles dispersed on a carrier containing USY zeolite. The impact of temperature, liquid hourly space velocity (LHSV), hydrogen to hydrocarbon (H2/HC) ratio and organic nitrogen (Norg) on the catalyst deactivation rate was first studied. The variables with the most significant impact on conversion loss were temperature and space velocity. Temperature directly influences the production rate of coke precursors, whereas space velocity affects the local concentration of feed contaminants along the reactor. Based on these results, the following operating conditions were selected to establish the final accelerated deactivation experimental protocol: T = 418 °C, LHSV = 3 h−1, H2/HC = 1500NL/L, P = 14 MPa, organic nitrogen content (Norg) = 150 ppm weight, total nitrogen content = 2500 ppm weight and a total time on stream of 30 days. Spent samples from this procedure presented similar properties to some industrial catalysts submitted to cycle lengths between 12 and 18 months. Both types of samples yield similar values of surface area and pore volume loss as well as a similar amount and nature of coke deposits. These results led to the qualitative validation of the protocol representativeness. This experimental procedure was then used to get more insight into the deactivation phenomenon. It was found that the organic nitrogen content of the feedstock is crucial, as it determines the ratio between available metal and acid sites. This ratio determines the reactions that take place and, therefore, the type of coke produced.

Rhenium Effect on the Performance of CoMoNi/γ‐Al2O3 Catalyst in Thiophene Hydrodesulphurization. Performance Evaluation and Process Kinetics

AbstractThe rhenium effect on the performance of CoMoNi/γ‐Al2O3 catalyst was studied in thiophene hydrodesulphurization. The unsulfided and freshly sulfided catalysts were characterized by N2 adsorption‐desorption, IR spectroscopy, X‐ray photoelectron spectroscopy (XPS) and total acidity. The effects of reaction temperature, pressure, and liquid hourly space velocity (LHSV) on thiophene HDS performance shown that the activity of the CoMoNiRe/γ‐Al2O3 catalyst for thiophene HDS was superior to that of the CoMoNi/γ‐Al2O catalyst, which was mainly ascribed to the higher acidic functional groups. Based on Langmuir‐Hinshelwood approach, a kinetic model for thiophene HDS over both catalysts have been developed. In this respect, two mechanisms have been considered, one hypothesizing that hydrogen is adsorbed on different active centers than thiophene (two‐centers mechanism) and the other considering one type of active centers. Based on statistical reasons, the kinetic model considering two types of active centers proved to be more adequate in representing the experimental results.

Selective hydrogenation of light cycle oil for BTX and gasoline production purposes

Abstract The study of the best experimental conditions and catalyst for the hydrogenation (HYD) of light cycle oil (LCO) for upgrading purposes was carried out. The objective was to examine the ability of two commercial hydrotreatment (HDT) catalysts for selective aromatic saturation. The effect of the hydrotreatment operation parameters (temperature, pressure, liquid hourly space velocity, H2/HC ratio) on the sulfur and nitrogen contents and in the saturation of aromatic hydrocarbons was also investigated. The goal was to obtain the highest conversion to mono-aromatic hydrocarbons from this di-aromatic (naphthalene derivatives) type feedstock, and at the same time to get reasonable hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) performance to avoid contaminant hydrocarbons for the next step (usually hydrocracking, HCK). An appropriate hydrotreated product with the highest concentration of mono-aromatic derivatives, a minimum reduction on the total aromatic content, and suitable decrements of sulfur and nitrogen compounds, was achieved using a cobalt-molybdenum supported on alumina catalyst, at 330 °C, 5.5 MPa, and a liquid hourly space velocity of 1.1 h−1. Additionally, the kinetics of the HDA was studied, assuming a lump characterization into tri-, di- and mono-aromatic and aliphatic hydrocarbons, pseudo-first-order reaction rates between these conversions, and thermal losses and diffusional resistances to be undetectable.

Thermodynamics and kinetics insights into naphthalene hydrogenation over a Ni-Mo catalyst

Hydrocracking represents an important process in modern petroleum refining industry, whose performance mainly relies on the identity of catalyst. In this work, we perform a combined thermodynamics and kinetics study on the hydrogenation of naphthalene over a commercialized NiMo/HY catalyst. The reaction network is constructed for the respective production of decalin and methylindane via the intermediate product of tetralin, which could further undergo hydrogenation to butylbenzene, ethylbenzene, xylene, toluene, benzene, methylcyclohexane and cyclohexane. The thermodynamics analysis suggests the optimum operating conditions for the production of monoaromatics are 400 °C, 8.0 MPa, and 4.0 hydrogen/naphthalene ratio. Based on these, the influences of reaction temperature, pressure, hydrogen/naphthalene ratio, and liquid hourly space velocity (LHSV) are investigated to fit the Langmuir-Hinshelwood model. It is found that the higher temperature and pressure while lower LHSV favors monoaromatics production, which is insensitive to the hydrogen/naphthalene ratio. Furthermore, the high consistence between the experimental and simulated data further validates the as-obtained kinetics model on the prediction of catalytic performance over this kind of catalyst.

Acid‐etched Pt/Al‐MCM‐41 catalysts for fuel production by one‐step hydrotreatment of Jatropha oil

AbstractEffective catalysts are indispensable for the preparation of fuel components from vegetable oils via the one‐step hydrothermal method. In this study, the Pt/MCM‐41 catalysts were prepared by etching with sulfuric acid, citric acid, or hydrochloric acid. The performance of the obtained Pt/MCM‐41 catalysts for the hydrothermal treatment of vegetable oils was evaluated in a fixed‐bed reactor using Jatropha oil as a model raw material (temperature = 360°C, liquid hourly space velocity = 1 h−1, hydrogen–oil ratio = 1000, and hydrogen pressure = 4 MPa). The modified catalysts were characterized using X‐ray diffraction, transmission electron microscopy, Brunauer–Emmett–Teller analysis, X‐ray fluorescence spectrometry, temperature‐programmed desorption of NH3, CO chemisorption, and pyridine adsorption infrared spectroscopy, respectively. Furthermore, the selectivity of various fuel components, including C8–C16 alkanes, C8–C16 iso‐alkanes, C8–C16 arenes, and C17–C18 alkanes, were analyzed based on the catalyst characteristics. Acid etching was found to decrease the surface area of Al‐MCM‐41 but increase the amount of acid sites, and among these acids, citric acid was proved as the priority additives, with better catalytic performance. Moreover, this catalyst exhibited the best conversion and the highest C8–C16 and C17–C18 selectivities.

Phenol Removal From Synthetic Wastewater by Adsorption Column

Adsorption column is used to perform the adsorption experiments of this work using continuous scheme. The operating parameters investigated in this work are; inlet pollutant concentration (10, 30, & 50 mg/L), Liquid hourly space velocity (5, 10, & 15 h−1), and thickness of activated carbon layer (5, 15, & 25 cm). The aim of this work is to investigate the possibility of removing high phenol concentration from a synthetic wastewater since the nearby North Refineries Company, Baiji, (Iraq) wastewater treatment plant receives high phenol concentration. Moreover, to investigate the effects of various operating parameters on the adsorption capacity, breakthrough, and exhaustion times. The results of this work show that activated carbon can remove high concentration of phenol (up to 50 mg/L) efficiently. The results also indicated that the adsorption capacity depends on inlet pollutant concentration, activated carbon thickness, and liquid hourly space velocity. Actual adsorption capacity is calculated and found to be different from adsorption capacity found depending on the adsorption models. The lowest and highest adsorption capacities are 0.428 and 9.02 mg/g respectively, while the corresponding values for actual adsorption capacities are 0.216 and 32.4 mg/g.

Lumped kinetic simulation of hydrodenitrogenation for full‐range middle‐low temperature coal tar

AbstractWith the increasingly prominent environmental problems and depletion of light petrochemical resources, the clean utilization of heavy oil has become the research focal area. The hydrodenitrogenation (HDN) experiments and kinetics of full‐range middle‐low temperature coal tar (MLCT) was studied on a fixed‐bed reactor with a Ni‐Mo/γ‐Al2O3 catalyst. Two kinds of three‐lumped kinetic models (K1 and K1.24) based on different reaction orders and high‐middle‐low reactivities were established and fitted by a simulated annealing algorithm for coal tar HDN reactions. The results presented good correspondence with experimental data following an average relative error of less than 0.3%. The effect of temperature, pressure, and liquid hourly space velocity (LHSV) on HDN of different reactivity nitrogen compounds (NCs) of MLCT was studied using the lumped kinetic models. Also, the difference between K1 and K1.24 models on the embodiment ability for HDN laws was also discussed from multiple perspectives. It has been observed that the HDN reactions of low and middle reactivity NCs are more influenced by LHSV; high temperature and pressure are more critical for the removal of low reactivity NCs, and low‐temperature or ‐pressure zone have larger effects on coal tar HDN reactions, especially at high LHSV; temperature has much more influence than pressure on the HDN effect, particularly towards the low reactivity NCs. The results of HDN laws for high reactivity NCs are concordant with K1 and K1.24 models. The K1.24 model is a bit more reasonable to reveal the HDN law of middle to low reactivity NCs.

Impacts of residence time on transformation of reaction intermediates and coking behaviors of acetic acid during steam reforming

Liquid hourly space velocity (LHSV) is a critical factor in steam reforming as it not only determines process capacity of reformer, but also affect the properties of the coke formed via impacting the activation of the reactants and the formation of the products. In this study, the impacts of LHSV on the properties of the coke formed in steam reforming of acetic acid over Ni/SBA-15 catalyst were investigated. The results indicated that the increasing LHSV promoted the formation of the gaseous by-products and accelerated coking, as the low residence time was not conducive for activation of steam. The coke formed at the higher LHSV was more aromatic and have more fused but defective ring structures. Furthermore, at the low steam ratio in reactants, the high LHSV could also promoted the retainment of the carbonyl functionality in the coke. These phenomena are mainly due to the higher abundance of the organic species on surface of the catalyst under the high LHSV. In addition, not only the cavity of the carbon nanotube but also other morphologies the coke such as carbon nanofiber, bamboo-like structure and string beads-like structure was closely related to the LHSV, as LHSV impacted the reaction intermediates formed and further on the precursors of the coke.

Synthesis of ZnO-CoO/Al2O3 nanoparticles and its application as a catalyst in ethanol conversion to acetone

In this work, ZnO-CoO/Al2O3 nanoparticles were synthesized and used as a catalyst for the dehydrogenation of ethanol to produce acetone. The catalyst was characterized by transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) to identify the particle size and surface area, which were found to be 50 ± 5 nm and 23 ± 2 m2/g, respectively. In addition, Raman Spectroscopy and X-ray diffraction (XRD) were used to scan the synthesized catalyst to determine the crystallinity of the bulk. The impact of reaction temperature, water/ethanol molar ratio, and inlet flow rate on the ethanol conversion and products’ yields was investigated. The results show that the optimum reaction conditions which give an ethanol conversion of 97% and the highest acetone yield (45%) are as follows: Temp. 400 °C, 7 mol H2O:1 mol ethanol, and liquid hourly space velocity (LHSV) 1.2 hr−1.

Optimization of Catalytic Distillation for the Synthesis of Dimethyl Carbonate by Response Surface Methodology

AbstractDimethyl carbonate (DMC) was synthesized from methanol and ethylene carbonate (EC) in a reactive distillation column by transesterification using different composite oxide catalysts. The catalysts were characterized by XRD, N2 adsorption‐ desorption, CO2‐TPD, and NH3‐TPD. The results show that the Zr−Al catalyst has the most strong base sites and weak acid sites compared with other catalysts. The synergistic effect of acid‐base sites makes it show excellent catalytic performance for DMC synthesis. The operation parameters including reflux ratio, feed molar ratio, liquid hourly space velocity (LHSV) and catalyst dosage were optimized by factorial design based on response surface methodology (RSM). The best optimization conditions was: reflux ratio=5.23 : 1, feed molar ratio=6.05 : 1, LHSV=0.48 h−1, catalyst dosage=119.04 ml, the relative error between measured value and predicted value is small, which indicated that the reliability of the optimized process is high.

Change in the Apparent Order at Different Temperatures and Catalyst Volumes: Hydrodesulfurization of KEC-AR.

This paper tackles the effect of reaction temperature on the apparent order of the hydrodesulfurization (HDS) reactions of an atmospheric residue (KEC-AR) derived from Kuwait Export Crude (KEC). Testing was carried out using a pilot plant consisting of five identical fixed-bed reactors arranged in series. A moderate-HDS-activity catalyst was used under a 120 bar (total) operating pressure, a feed flow rate of 120 mL per hour (mL/h), and a hydrogen-to-feed ratio of 1000 mL/mL. The liquid hourly space velocity (LHSV) varied by 4.0, 2.0, 1.0, 0.5, and 0.25 relative to the catalyst accumulative volumes in the five reactors. Testing was conducted between 360 and 420 °C with a temperature increase of 10 °C each time. Product samples were collected between the reactors using customized inter-reactor sampling systems that operate under the pilot plant’s total pressure. The results showed that the HDS apparent order decreases with an increase in reaction temperature. The order dropped from 4.9 at 360 °C to 1.62 at 420 °C. Using the least-squares method (LSM), we demonstrated that the apparent overall orders are aggregates of several first-order reactions occurring consecutively at different rates and dependent on sulfur total disappearance. On the other hand, we showed that the apparent overall orders are aggregates of several reactions of different orders occurring simultaneously and independently of sulfur total disappearance. The first-order reactions’ activation energy was found to be 22.1 kcal/mol and in total agreement with that reported in the literature for the sulfur removal from KEC-AR.

Pt/CeO2 catalyst synthesized by combustion method for dehydrogenation of perhydro-dibenzyltoluene as liquid organic hydrogen carrier: Effect of pore size and metal dispersion

Liquid organic hydrogen carrier (LOHC) is a chemical hydrogen storage method that stores hydrogen in the form of liquid organics. Dibenzyltoluene (DBT) is a promising LOHC material due to its high storage density, low ignitability, and low cost. In this study, Pt/Al2O3 and Pt/CeO2 catalysts are synthesized using a combustion nanocatalyst synthesis method called the glycine nitrate process (GNP) to obtain high catalytic activity for the dehydrogenation of perhydro-dibenzyltoluene (H18-DBT). Pt/CeO2 exhibits much faster dehydrogenation than Pt/Al2O3, 80.5%/2.5 h versus 3.5%/2.5 h. To investigate the causes of the difference in the dehydrogenation rates, microstructural characterization by N2 physisorption, CO chemisorption and transmission electron microscopy analysis are conducted, and the catalytic activities are evaluated at various liquid hourly space velocities (LHSVs). The differences in dehydrogenation can be attributed to the mass transport of liquid H18-DBT into the catalyst pores being slow due to the small pores in Pt/Al2O3, which is a rarely addressed issue for other LOHC materials. This is because many LOHC materials are dehydrogenated at the gas phase, which has higher diffusivity than that of the liquid phase. Pt/CeO2 synthesized by the GNP is also compared with a commercial Pt/Al2O3 catalyst. The commercial Pt/Al2O3 catalyst shows a dehydrogenation of 17.8%/2.5 h, which is much slower than that of Pt/CeO2 synthesized by the GNP, at 80.5%/2.5 h.

Catalytic Hydroprocessing of White Pine Pyrolysis Bio-Oil over Cobalt-Molybdenum Carbide in a Continuous Packed-Bed Reactor

Catalytic hydroprocessing of white pine pyrolysis bio-oil over cobalt-molybdenum (CoMo) carbide supported on biochar was carried out in a continuous fixed-bed reactor at a temperature between 350 and 425 °C, hydrogen pressure between 7 and 12.5 MPa, and liquid hourly space velocity (LHSV) of 0.1–1.0 h−1 with a hydrogen flow rate of 500 mL/min. The results showed that the CoMo carbide catalyst can effectively improve the yield and qualities of hydrotreated bio-oil. Under the preferred reaction conditions of 400–425 °C, 10 MPa H2, and LHSV 0.3 h−1, the yield, the carbon content, the carbon recovery ratio, and the higher heating value of the upgraded bio-oil reached 24.2–25.7% of the feed, 86.5–87.4%, 48.1–52.1%, and 41.8–43.9 MJ/kg, respectively. The oxygen content, total acid number, and moisture of the hydrotreated bio-oil decreased to 0.1–1.6 wt%, aromatics > olefins > paraffins > naphthenes.

Optimization of kerosene from a one-step catalytic hydrogenation of castor oil over Pt-La/SAPO-11 by response surface methodology

A one-step continuous catalyzed hydrogenation preparation of bioaviation kerosene was prepared from castor oil with a molecular probe in a high-pressure microfixed bed. The catalyst was Pt-La/SAPO-11, which was synthesized by the impregnation of Pt, as the active metal component, and metal auxiliaries. The effect of adding metal auxiliaries into the bifunctional metal was evaluated by XRD, XRF, BET, TEM, and Py-IR techniques, and it was confirmed that the hydrodeoxygenation performance, the selectivity of C8–C16 alkanes, the selectivity of C8–C16 isoalkanes, and the selectivity of C8–C16 arenes were all improved. Combined with a Box-Behnken central composite design, the reaction temperature, pressure, liquid hourly space velocity (LHSV), and hydrogen/oil ratio (hydrogen volume/castor oil volume) were selected as the four critical factors for the three levels of selectivity. The response surface method (RSM) was selected to establish a mathematical model with a second-order quadratic equation and optimize the process parameters for enhancing the selectivity of C8–C16 alkanes. The optimization conditions of the four process parameters were found to be a temperature of 405 °C, a pressure of 3.9 MPa, an LHSV of 0.93 h−1, and a hydrogen/oil ratio of 990 NmL mL−1. Three verification experiments showed that the selectivity of C8–C16 alkanes was 58.76%.

Hydrogenation of Aqueous Acetic Acid over Ru-Sn/TiO2 Catalyst in a Flow-Type Reactor, Governed by Reverse Reaction

Ru-Sn/TiO2 is an effective catalyst for hydrogenation of aqueous acetic acid to ethanol. In this paper, a similar hydrogenation process was investigated in a flow-type rather than a batch-type reactor. The optimum temperature was 170 °C for the batch-type reactor because of gas production at higher temperatures; however, for the flow-type reactor, the ethanol yield increased with reaction temperature up to 280 °C and then decreased sharply above 300 °C, owing to an increase in the acetic acid recovery rate. The selectivity for ethanol formation was improved over the batch process, and an ethanol yield of 98 mol % was achieved for a 6.7 min reaction (cf. 12 h for batch) (liquid hourly space velocity: 1.23 h−1). Oxidation of ethanol to acetic acid (i.e., the reverse reaction) adversely affected the hydrogenation. On the basis of these results, hydrogenation mechanisms that include competing side reactions are discussed in relation to the reactor type. These results will help the development of more efficient catalytic procedures. This method was also effectively applied to hydrogenation of lactic acid to propane-1,2-diol.