The process for catalytic incineration of waste gas on IC-12-S102 platinum glass fiber catalyst

The process for catalytic afterburning of volatile organic compounds (VOCs) in waste industrial gases was developed on the basis of a new platinum glass fiber catalyst (GFC) IC-12-S102 with low platinum content (∼0.02 wt %). The catalyst was shown to be more effective than the known industrial afterburning catalysts. The way of glass fiber catalyst loading to a reactor in the form of vertical spiral cartridges, structured with wire mesh of bulk weaving is described. The successful application of the IC-12-S102 catalyst was confirmed by its operation at OAO Nizhnekamskneftekhim in the process of waste gases afterburning in an industrial reactor with cleaned gases capacity up to 15000 m³/h. During the reactor operation in harsh conditions (low oxygen content, high content of water vapor), the degree of gas cleaning was 99.5–99.9% and the residual VOC content in the purified gases was no higher than 10–15 mg/m³. For more than 15 months of catalyst operation, the degree of gas purification was not reduced; thus, overall lifetime of the IC-12-S102 catalyst may be substantially longer than the life of well-known industrial afterburning catalysts.     

Analysis of the deactivation of Claus alumina catalyst during its industrial exploitation

Change in the activity of AO-NKZ-2 (AO-MK-2) alumina catalyst in the Claus reaction and transformations of carbonyl sulfide during operation over four years in the Claus reactor at the Magnitogorsk Metallurgical Combine’s coke-oven gas purification shop were studied at an average temperature of 245–260°C and a volume velocity of ∼2000 h⁻¹. The rate constants of the Claus reactions and COS transformation were determined, and the changes in the active surface area of the catalyst were investigated. Fundamental discrepancies in the rate and deactivation mechanism of the Claus catalysts were revealed with respect to the reactions of the conversion of hydrogen sulfide and carbonyl sulfide.     

Catalytic synthesis of triazine compounds using a flexible technology

Based on laboratory pilot studies, we have developed a flow sheet for the catalytic synthesis of triazine compounds from carbamide using a flexible technology and a catalyst for this process. The main process parameters are as follows: a carbamide melt is fed into the reactor under a pressure of 0.8 MPa at 140–160°C; the volume rate of feeding the circulating gas into the reactor is 500–750 h⁻¹, its temperature is 350–500°C, and the melt-to-gas mass ratio is 1: (7–9). The temperature of synthesis in the reactor is 350–450°C; the pressure in the reactor is 0.1–0.2 MPa. The sublimation temperature is 180–200°C. The conversion of carbamide is ∼98%. The content of the target component in the product is ∼98.8%. Depending on the composition of the circulating gas, it is possible to obtain products of melamine, cyanuric acid, or melamine cyanurate. A catalyst in the form of promoted active aluminum oxide with an inner surface of 300 to 400 m²/g and a technique for its preparation have been developed.     

Developing a method for increasing the service life of a higher paraffin dehydrogenation catalyst,based on the nonstationary kinetic model of a reactor

The service life of an industrial catalyst can be prolonged by improving the technological conditions of its operation. This allows us to maximally eliminate the catalyst deactivation factors. A specific feature of the catalytic dehydrogenation of hydrocarbons is its nonstationarity produced by the deactivation of catalysts. The results of modeling the industrial catalytic process of C₉-C₁₄ paraffin dehydrogenation—the key stage in the production of linear alkylbenzenes—is discussed in this paper. We consider (1) thermodynamic analysis of reactions by means of quantum chemistry, (2) estimation of the kinetic model’s parameters by solving the inverse kinetic problem, (3) selection of an equation that describes the coke deactivation of a catalyst, and (4) development of a method for increasing the service life of a dehydrogenation catalyst using a nonstationary model based on the quantitative consideration of the water added to a reactor within a temperature range of 470–490°C. The higher alkane dehydrogenation flowsheet proposed on the basis of these models allows us to predict the operation of a reactor in different water supply regimes. It is shown that the service life of a catalyst grows by 20–30% on the average, if water is fed by increasing portions.     

The Effect of Acid Strength on the Conversion of Methanol to Olefins Over Acidic Microporous Catalysts with the CHA Topology

The present work addresses the influence of acid strength on the stability and product selectivity of microporous catalysts with CHA framework type. The two studied catalysts, H-SAPO-34 and H-SSZ-13, have the same topology, density of acid sites (approximately one acid site per cage), and crystal size (0.2–2 microns), but their acid strength differ due to the framework composition. The difference in acid strength was determined by infrared spectroscopy, using CO as probe molecule. Catalytic tests were performed in a fixed bed flow reactor at 300–425 °C and WHSV = 6.0 h⁻¹. It was observed that the acid strength has significant influence on reaction rates, enhancing the production rate of olefins in the reactor effluent as well as aromatics retained in the catalyst pores and leading to a lower optimal temperature of operation for the more acidic H-SSZ-13 catalyst. The activation and deactivation patterns and the intermediates formed are very similar for the two materials. The ethene to propene ratio increases with temperature and time on stream for both catalysts, and is higher over the more acidic H-SSZ-13 catalyst at similar reaction conditions.     

Pilot tests of a new domestic ZhKD catalyst for the dehydrogenation of isoamilenes into isoprene

At the Synthetic Rubber Plant of OAO Nizhnekamskneftekhim, the dehydrogenation of isoamilenes into isoprene is currently performed on KDOM-08 catalysts with an insufficiently high yield of isoprene throughout the period of its industrial operation. More stable and highly active catalysts must be used to make the process more efficient. Under Russian Federation Government Decree No. 218, ZhKD-1 and ZhKD-2 iron-potassium catalysts have been developed by improving their formulas and optimizing their phase composition through selecting the proper ratio of initial compounds. To evaluate the possibility of transitioning to the new domestically-produced iron-potassium catalysts, we have performed pilot tests of the ZhKD-1 and ZhKD-2 catalysts in the dehydrogenation of methylbutenes into isoprene in adiabatic flow fixed-bed reactors at the Synthetic Rubber Plant of OAO Nizhnekamskneftekhim. The KDOM-08 catalyst used in the amount of 25 t in reactor 1 of the first system is taken as a base for comparison. The ZhKD-1 and ZhKD-2 catalysts are loaded into parallel reactors 7 and 8 of the fourth system. The KDOM-08 catalyst is shown to operate more efficiently under industrial conditions at loads of 1.0–2.0 t/h for 1000–3000 h, after which its performance characteristics deteriorate due to its gradual deactivation. The ZhKD-1 and ZhKD-2 catalysts are substantially superior to their industrial analogues in isoprene yield. It has been found that the ZhKD-2 catalysts operate more efficiently at even longer runs (4000–5000 h) and feedstock flow rates of 1.0–2.0 t/h, and the ZhKD-1 catalysts exhibits better activity (30–33 %) and selectivity (87–92 %) at higher loads of 2.3–3.0 t/h for up to 5000 h. From our analysis of the catalysts’ operation over the last 1000 h, it follows that at the same process temperatures (619°C) and feedstock loads (2.5 t/h), the ZhKD-1 and ZhKD-2 catalysts operate at a lower steam dilution coefficient (6.1 t/t) than the KDOM-08 catalyst (6.8 t/t). The rebuilding of reactors 7 and 8 allows the loaded catalyst mass to be reduced from 25 to 17 t, thereby almost doubling the daily output of isoprene per ton of catalyst. It is obvious that higher activity and selectivity along with smaller loads makes the use of the ZhKD-1 and ZhKD-2 catalysts economically profitable.     

Kinetics of palm oil transesterification in a batch reactor

Methyl esters were produced by transesterification of palm oil with methanol in the presence of a catalyst (KOH). The rate of transesterification in a batch reactor increased with temperature up to 60°C. Higher temperatures did not reduce the time to reach maximal conversion. The conversion of triglycerides (TG), diglycerides (DG), and monoglycerides (MG) appeared to be second order up to 30 min of reaction time. Reaction rate constants for TG, DG, and MG hydrolysis reactions were 0.018–0.191 (wt%·min)⁻¹, and were higher at higher temperatures and higher for the MG reaction than for TG hydrolysis. Activation energies were 14.7, 14.2, and 6.4 kcal/mol for the TG, DG, and MG hydrolysis reactions, respectively. The optimal catalyst concentration was 1% KOH.     

Performance studies of various cracking catalysts in the conversion of canola oil to fuels and chemicals in a fluidized-bed reactor

Studies were conducted at atmospheric pressure at temperatures in the range of 400–500°C and fluidizing gas velocities in the range of 0.37–0.58 m/min (at standard temperature and pressure) to evaluate the performance of various cracking catalysts for canola oil conversion in a fluidized-bed reactor. Results show that canola oil conversions were high (in the range of 78–98 wt%) and increased with an increase in both temperature and catalyst acid site density and with a decrease in fluidizing gas velocity. The product distribution mostly consisted of hydrocarbon gases in the C₁–C₅ range, a mixture of aromatic and aliphatic hydrocarbons in the organic liquid product (OLP) and coke. The yields of C₄ hydrocarbons, aromatic hydrocarbons and C₂–C₄ olefins increased with both temperature and catalyst acid site density but decreased with an increase in fluidizing gas velocity. In contrast, the yields of aliphatic and C₅ hydrocarbons followed trends completely opposite to those of C₂–C₄ olefins and aromatic hydrocarbons. A comparison of performance of the catalysts in a fluidized-bed reactor with earlier work in a fixed-bed reactor showed that selectivities for formation of both C₅ and iso-C₄ hydrocarbons in a fluidized-bed reactor were extremely high (maximum of 68.7 and 18 wt% of the gas product) as compared to maximum selectivities of 18 and 16 wt% of the gas product, respectively, in the fixed-bed reactor. Also, selectivity for formation of gas products was higher for runs with the fluidized-bed reactor than for those with the fixed-bed reactor, whereas the selectivity for OLP was higher with the fixed-bed reactor. Furthermore, both temperature and catalyst determined whether the fractions of aromatic hydrocarbons in the OLP were higher in the fluidized-bed or fixed-bed reactor.     

Activity monitoring of Claus catalysts in sulfur recovery units

Methodical principles of catalyst activity monitoring in Claus reactors based on the determination of the rate constant of the reaction of hydrogen sulfide conversion at catalyst temperatures lower than 280°C are discussed. The procedure is justified by data from laboratory experiments (in the range of concentrations [H₂S]₀ = 1.5–7 vol %), pilot tests ([H₂S]₀ = 0.8–37.4 vol %) of an alumina-based catalyst AO-NKZ-2 produced by ZAO Novomichurinsk Catalyst Plant, and by the results of its test in the Claus reactor of the department for coke oven gas purification of by-product-coke plant at the OAO Magnitogorsk Integrated Iron-and-Steel Works. The procedure is recommended for reliable monitoring of the current activity and estimation of the residual life of catalysts in the Claus industrial reactors operating under conditions of substantial variations in the composition of the process gas, as well as for comparative estimates of catalyst activity in the Claus process.     

Fatty methyl ester hydrogenation to fatty alcohol part II: Process issues

Fatty alcohols are produced by hydrogenating fatty methyl esters in slurry phase in the presence of copper chromite catalyst at temperatures of 250–300°C and hydrogen pressures of 2000–3000 psi. The fatty methyl ester, catalyst, and hydrogen are fed to the reactor cocurrently. The product slurry is passed through gas-liquid separators and then through a continuous filtration system for removal of the catalyst. A portion of the used catalyst in crude alcohol is recycled to the hydrogenator. The overall efficiency of the process depends upon the intrinsic activity, life, and filterability of the catalyst. The fatty alcohol producer therefore requires a catalyst with high activity, long life, and good separation properties. The main goal of the present laboratory investigation was to develop a superior copper chromite catalyst for the slurry-phase process. Two copper chromite catalysts, prepared by different procedures, were tested for methyl ester hydrogenolysis activity, reusability, and filtration characteristics. The reaction was carried out in a batch autoclave at 280°C and 2000–3000 psi hydrogen pressure. The reaction rates were calculated by assuming a kinetic mechanism that was first-order in methyl ester concentration. The catalyst with the narrower particle size distribution was 30% more active, filtered faster, and maintained activity for several more uses than the catalyst with the broader particle size distribution. X-ray photoelectron spectroscopy data showed higher surface copper concentrations for the former catalyst.     

Intrinsic kinetics of one-step dimethyl ether synthesis from hydrogen-rich synthesis gas over bi-functional catalyst

The reaction kinetics of the dimethyl ether synthesis from hydrogen-rich synthesis gas over bi-functional catalyst was investigated using an isothermal integral reactor at 220–260°C temperature, 3–7 MPa pressure, and 1,000–2,500 mL/g·h space velocity. The H₂/CO ratio of the synthetic gas was chosen between 3 : 1 and 6 : 1. The bi-functional catalyst was prepared by physically mixing commercial CuO/ZnO/Al₂O₃ and γ-alumina, which act as methanol synthesis catalyst and dehydration catalyst, respectively. The three reactions, including methanol synthesis from CO and CO₂ as well as methanol dehydration, were chosen as independent reactions. The Langmuir-Hinshelwood kinetic models for dimethyl ether synthesis were adopted. Kinetics parameters were obtained using the Levenberg-Marquardt mathematical method. The model was reliable according to statistical and residual error analyses. The effects of different process conditions on the reactor performance were also investigated.     

Generalizing operation experience of CA-1P granulated ammonia synthesis catalyst for a column daily capacity of 200, 600, and 1360 tons of NH3

The 15-year operation experience of the CA-1P granulated ammonia synthesis catalyst is generalized for a column daily capacity of 200, 600, and 1360 tons of ammonia. When prepared by continuous iron melting, with the simultaneous additions of promoters, the CA-1P granulated ammonia synthesis catalyst is more advantageous than ground catalysts (1.5- to 1.7-fold faster reduction at the lower temperature of 360°C and higher activity), and its production prospective was shown. On the basis of the developed technology, the NIAP-08-01 catalyst was prepared to pass through industrial tests in ammonia synthesis columns of various design (tube and multiple-shell) and daily capacity (200, 600, and 1360 tons). Various loading schemes of the CA-1P catalyst were tested, using fine (3–5 and 5–7 mm) fractions up to 40%. No increasing resistance in catalyst layer was observed. Use of the CA-1P catalyst increased column efficiency by 5–10%. Generalized operation experience of the CA-1P (NIAP-08-01) catalyst enabled to recommend it for a column daily capacity of 1360 tons in columns with radial gas flow.     

Copper catalysts in the selective hydrogenation of soybean and rapeseed oils: II. The effect of a hydrogen flow over copper chromite catalyst

Time required for hydrogenation of soybean and rapeseed oils to 1–2% linolenate content with a copper chromite catalyst is reduced 40–60% if the dead-end system is replaced with a procedure using a flow of hydrogen through the reactor. The effect is ascribed to the removal of oxidation products, acting as catalyst poisons and the water which is formed during reduction of the catalyst. Selectivity towards the linolenate compound is nearly unchanged.     

Synthesis of ethylene and propylene on a SAPO-34 silica—alumina—phosphate catalyst

A process for the preparation of ethylene and propylene from methanol on a microporous silica—alumina—phosphate SAPO-34 catalyst is described. The influence of the temperature and the nature and concentration of the diluting agent on the catalyst activity, its selectivity with respect to C₂₌-C₄₌ olefins, and ability to be regenerated were studied. The SAPO-34 catalyst was shown to be highly effective in the selectivity of ethylene and propylene formation; the total yield of C₂₌-C₄₌ olefins at 350–450°C was 77–84% and methanol conversion was up to 96–99%. In the conversion of methanol under helium at 450°C, the yield of ethylene (∼36%) was higher than at 375°C (∼29%), while the yield of propylene (∼30%) was lower (∼38%). The use of water and helium vapors as a diluent increased the yield of ethylene to ∼36% at 375°C and to ∼50% at 450°C. In the conversion of methanol at 450°C in water vapors without helium, the yield of ethylene reached ∼44–49% and the yield of propylene was 24–29%. The C₃₌ to C₂₌ ratio in the process varied from ∼0.5 to 1.5. The high efficiency of the SAPO-34 catalyst is the consequence of the microporous structure of zeolite and the high content of acid centers of medium strength. In the course of methanol conversion, the catalyst was deactivated due to coking. After regeneration with air at 550°C, the catalyst activity was completely restored, while the crystal structure and the acid properties did not change. The activity of the catalyst in a cycle is prolonged if water vapors are used as a diluent and the catalyst is processed at a high temperature with vapors. The industrial processes for the production of ethylene and propylene from nonpetroleum materials are not used in Russia. The results of this study are comparable to the data obtained from the UOP/Norsk Hydro process on the SAPO-34 catalyst. The catalyst can be recommended for further trials on an FCC type pilot plant with a moving catalyst bed.     

Characteristics of carbon dioxide hydrogenation in a fluidized bed reactor

Characteristics of CO₂ hydrogenation were investigated in a fluidized bed reactor (0.052 m IDxl.5 m in height). Coprecipitated Fe-Cu-K-Al catalyst (d_ρ=75–90 Μm) was used as a fluidized solid phase. It was found that the CO₂ conversion decreases but the CO selectivity increases, whereas the space-time-yield attains maximum values with increasing gas velocity. The CO₂ conversion has increased, but CO selectivity has decreased with increasing hydrogenation temperature, pressure or H₂/CO₂ ratio in the fluidized bed reactor. Also, the CO, conversion and olefin selectivity appeared to be higher in the fluidized bed reactor than those of the fixed bed reactor. Presented at the Int’l Symp. on Chem. Eng. (Cheju, Feb. 8–10, 2001), dedicated to Prof. H. S. Chun on the occasion of his retirement from Korea University     

Oxidation of Butane to Maleic Anhydride using Vanadium Phosphate Catalysts: Comparison of Operation in Aerobic and Anaerobic Conditions using a Gas-gas Periodic Flow Reactor

The use of a periodic flow reactor is described for the oxidation of butane to maleic anhydride to compare the catalytic performance of vanadium phosphate catalysts operating under aerobic and anaerobic conditions. It is found that for the catalyst prepared via a standard VPO method, operation in the absence of oxygen leads to a very small enhancement in selectivity when butane concentrations in the range 0.9–2.9% are used. Operation in the absence of oxygen leads to very small differences in conversion such that the overall yield is enhanced and this effect is maximised for reactor feeds containing 1.5% butane. However, the enhancement is negligible when the catalyst is operated at high conversion required for commercial operation, indicating that reactors operating with continuous flow with aerobic conditions are preferred. Similar experiments are conducted for a catalyst prepared by the VPD method and, in contrast, this catalyst gives lower butane conversion and maleic anhydride selectivity when operated in the absence of oxygen.     

Coke formation on an industrial reforming Pt–Sn/γ‐Al2O3 catalyst

The characterization of the coke deposited on an industrial Pt–Sn/γ‐Al₂O₃ catalyst, used in a continuous reforming process, was performed with AFM, XRD, FTIR, EPR, NMR, TG‐DTG and DTA techniques. Composition, structure and location of the coke on the catalyst were investigated. The coke was predominantly deposited on the catalyst surface and in the interstices between the catalyst particles. Its content increased along the reactor from top to bottom. Coke was deposited in the form of uniform films and clusters of three‐dimensional disks with diameters between 0.12 and 0.18 μm. It had a pseudo‐graphite structure produced by the dehydrogenation and polymerization of the aromatic precursor compounds. The coked catalyst showed a good combustion behavior; it was regenerated below 550°C. These results are important to elucidate the coke formation mechanism, to generate new continuous reforming catalysts, and to optimize the reactor operation parameters. This revised version was published online in July 2006 with corrections to the Cover Date.     

Development of an optical fiber monolith reactor for photocatalytic wastewater Treatment

A photocatalytic reactor, which employs a ceramic multi-channel monolith as a support for TiO₂ and bare quartz fibers inserted inside the monolithic channels as both a light-transmitting conductor and a support for TiO₂, was constructed and tested for water treatment by investigating the photocatalytic degradation of o-dichlorobenzene (DCB) and phenanthrene (PHE). This configuration provides a higher surface area for catalyst coating per unit reactor volume compared to the continuous annular reactor (CAR) and optical fiber reactor (OFR). The light distribution profile inside each cell of the monolith is analyzed. Exponential decay of light was observed in propagation along the quartz fiber core and penetration into the TiO₂ film. Optimum thickness of TiO₂ layer on the optical fiber was found to be ≈ 0.4 μm in this study. The kinetics of DCB and PHE degradation were pseudo-first order. The effect of the water flow velocity was investigated and showed that the operation was in the mass transfer control regime. Overall rate constants were extracted from the experimental data; and these were then used to calculate the apparent quantum efficiency of photocatalytic degradation. Greater apparent quantum efficiency was observed for the optical fiber monolithic reactor (OFMR) compared with that of the CAR.     

Kinetics of liquid phase hydrogenation of cottonseed oil with nickel catalysts

The hydrogenation of cottonseed oil has been carried out in a batch reactor using both unmodified and chromia modified nickel catalysts. The process variables include chromium to nickel atomic ratio (0.00–0.35), catalyst particle size (200–400 micron), temperature (120–140°C) and pressure (5–10 bar). Chromia was found to suppress the stearate formation completely, although it retarded the overall hydrogenation activity of nickel. Its optimum content in the catalyst was found to be 0.17 Cr/Ni atomic ratio; the data corresponded to 5 hr reaction time. The kinetics of the process was tested and found to follow a first order reaction with respect to linoleate and half order with respect to hydrogen. The activation energy was found to be 11.8 kcal/mole.     

Effect of the granulometric composition of microspherical catalyst on the product yield for the dehydrogenation of <Emphasis Type="Italic">iso</Emphasis>-butane

The effect of the granulometric composition of microspherical KDI alumina-chromia catalysts on variation of the height and density of a fluidized bed was analyzed during pilot industrial testing at the OAO Nizhnekamskneftekhim iso-butane dehydrogenation plant. It was ascertained that one of the factors determining the acceleration of the cracking reactions was a rise in temperature to 600–610°C in the upper part of the reactor at the level of grid no. 10 due to the reduction of the upper boundary of the fluidized bed as a result of carryover from the reactor-regenerator system of catalyst particles smaller than 20 microns. The formation of a stable fluidized bed on the upper grid of the reactor depends on the content of 20–40 μm particles within the circulating catalyst. In order to compensate for the carryover of the catalyst, it is recommended that the mixture of catalysts accumulated in the first and second electrofilter fields be loaded into the system as well. This load consists of ∼25 wt % of the fraction with particle sizes of 20–40 μm and is as good the initial KDI in terms of catalytic parameters, ensuring stabilization of the fluidized bed height at a level of 52%, lowering of the temperature at the tenth grid of the reactor to 568°C, reduction of the yield of cracking products to 4.0 wt %, a 3% increase in the average daily output of iso-butylene, and a 7% decrease in the consumption of iso-butane. Recovery of the irrevocable carryout of the catalyst from the system and the formation of a stable fluidized bed were achieved by alternating the additional loading of the catalysts from the first and second fields of the electrofilter and the initial KDI with optimized fraction composition at a 4: 1 ratio.