Propylene Oxide Production Research Articles

Density functional and chemical model study of the competition between methyl and hydrogen scission of propane and β-scission of the propyl radical

In this work, we study the competence between the reactions of hydrogen and methyl scission during thermal cracking and combustion of propane, the emergence of the two isomers of the propyl radical, n-propyl and i-propyl, and their subsequent β-scission reaction to ethene and methyl radical. The purpose of the study was to analyze the accuracy of density functional (DFT) methods as applied on this relatively well-known subset of the reactions implied in the production of propylene oxide from propane and propene. Conventional (B3LYP, B3PW91) and state-of-the-art (PBE0, M06, BMK) DFT methods were employed, and their accuracy checked against experimental data and calculations performed using model chemistries (complete basis set CBS-4M, QB3, and APNO, and G4 methods) and ab initio methods (MP2, CCSD(T) with a large 6-311 ++G(3df,2pd) basis set). The results obtained at the BMK level for the thermodynamics of the reactions are closer to experimental data than those afforded by any other DFT method and very similar actually to CBS or CCSD(T) results, even if a medium size basis set is used. Activation energies determined using twoand three-parameter Arrhenius equations are also very good, but the preexponential factors are incorrect. Tunneling and internal rotation corrections must be applied to obtain semiquantitative results.

Propylene Oxide Makers Expand

Working with local partners, Huntsman Corp. and Shell Chemicals are planning new propylene oxide facilities to meet growing demand from Asian customers for the insulating foam raw material. Huntsman’s technology will form the basis of a joint venture with Sinopec affiliate Jinling to build a 550 million-lb-per-year propylene oxide plant in Nanjing, China, by the end of 2014. The plant will also produce 1.6 billion lb of coproduct methyl tert-butyl ether, a fuel additive used to improve air quality. Jinling will own 51% of the venture, to be known as Nanjing Jinling Huntsman New Materials, and Huntsman will own the balance. The two say the facility will cost $750 million to build. The deal with Jinling will “further our global expansion,” says Huntsman CEO Peter R. Huntsman. A spokesman adds that increased propylene oxide production in China will support a rising standard of living there. Shell’s propylene oxide technology will ...

ChemInform Abstract: Exploring Computational Design of Size‐Specific Subnanometer Clusters Catalysts

AbstractReview: 245 refs.

Exploring Computational Design of Size-Specific Subnanometer Clusters Catalysts

Computational design of catalysts is currently an area of significant interest. While this area has made great strides in recent years, these methods have mainly been applied to solid heterogeneous catalysts. An emerging class of catalysts with very promising properties is that constructed from clusters of atoms at or below the nanoscale. The use of computational catalyst design methods for the construction and optimization of subnanometer clusters, however, has not yet been extensively explored. In this review, we discuss recent work on subnanometer catalysts in our group and discuss how computational catalyst design principles are being explored for this class of materials. Specifically, the origin of activity and selectivity for supported metal clusters that catalyze the production of propene and propylene oxide are discussed along with the implications of these studies for implementing a descriptor-based catalyst optimization. The extension of these ideas for designing a catalyst for methanol decomposition is then discussed and an application of a descriptor-based scheme for the optimization of methanol decomposition by subnanometer catalyst is shown.

Direct gas-phase photocatalytic epoxidation of propylene with molecular oxygen by photocatalysts

The photocatalytic epoxidation of propylene by molecular oxygen is one of the best methods to produce propylene oxide (PO) from the environmental viewpoints. The key is using photo-energy to achieve high PO selectivity and yield at mild conditions. A series of photocatalysts including SiO 2, TiO 2, V-Ti/MCM-41, V 2O 5/SiO 2, Au/TiO 2 and TS-1, were used to evaluate their performance in the photo-epoxidation. The photocatalytic epoxidation of propylene was carried out in the gas mixture of C 3H 6:O 2:N 2 = 1:1:18 at atmospheric pressure. In addition to PO, other products, such as propionaldehyde, acetone, acetaldehyde, ethanol and methanol, were detected. The results indicated that the most favorable photocatalysts for photocatalytic epoxidation were silicates supported group. The highest PO formation rate of 114 μmol g cat −1 h −1 with selectivity of 47% was obtained over V-Ti/MCM-41 on stream after 4 h at 50 °C and atmospheric pressure under UVA irradiation of 0.2 mW/cm 2. In addition, the selectivity of products was very stable on stream. A possible reaction mechanism was proposed based on the knowledge of species presented during the photocatalytic reaction.

Epoxidation of propylene to propylene oxide catalyzed by large-grain TS-1 in supercritical CO 2

Large-grain titanium silicalite (TS-1, 3.0 μm long), which is a low-cost catalyst that can easily be separated from the product and exhibits an efficient catalyst recovery, was synthesized using tetrapropylammonium bromide (TPABr) as the template. However, it exhibited very poor catalytic activity in the traditional organic solvent compared with small-grain TS-1. The epoxidation of propylene to propylene oxide (PO) using the large-grain TS-1 as the catalyst and H 2O 2 as the oxidant in a supercritical CO 2 (scCO 2) medium was then investigated. The effects of the CO 2 pressure, reaction temperature, propylene pressure, cosolvent (methanol) concentration, and reaction time on the epoxidation reaction in scCO 2 were investigated and compared with those of the reaction in methanol. The use of scCO 2 as the reaction medium significantly improved the catalytic activity of the large-grain TS-1 and increased the PO yield from 50.1 to 83.5%. The effect of alkaline components [NaOH, NaHCO 3, urea, and (NH 4) 2CO 3] on the epoxidation reaction in scCO 2 was also investigated. The addition of alkaline components had a positive effect on the selectivity to PO as well as to H 2O 2 utilization. The addition of (NH 4) 2CO 3 yielded the best results, with the H 2O 2 conversion, PO selectivity, H 2O 2 utilization, and PO yield reaching 98.7%, 95.2%, 94.3%, and 88.6%, respectively. Therefore, a novel approach to PO production is introduced, which provides a basis as well as technical parameters for its further industrialization.

Oxidation of Propylene with Oxygen and Air in a Barrier Discharge in the Presence of Octane

Oxidation of propylene with oxygen, air and a mixture of nitrogen–oxygen in a barrier discharge is investigated. The selectivity towards formation of propylene oxide in pure oxygen is shown to be as high as 45 wt% and the propylene conversion ratio is found to be 12.9 wt%. In the oxidation with air, the propylene oxide selectivity is 23 wt%, while the conversion is 7.5 wt%. The values of propylene conversion and selectivity towards formation of propylene oxide in a barrier discharge are consistent with those obtained by the thermocatalytic methods for production of propylene oxide.

The Effects of Cofeeding Chlorinated Hydrocarbons in the Direct Epoxidation of Propylene by Molecular Oxygen

Chlorine does it again: Similar to the ethylene epoxidation, the introduction of chlorinated hydrocarbon (CHC) additives to the C3H6/O2 feed enables the steady production of propylene oxide (PO), albeit at a slight decrease in propylene conversion.

Au/TiO 2@SBA-15 nanocomposites as catalysts for direct propylene epoxidation with O 2 and H 2 mixtures

A nanostructured Au/TiO 2@SBA-15 catalyst has been prepared and applied in propylene epoxidation with a mixture of O 2/H 2. The mesopores of SBA-15 were first deactivated by grafting of hydrophobic groups. Titanium was then selectively grafted in the micropores of SBA-15 by reaction with titanium isopropoxide followed by calcination and deposition of Au nanoparticles. The nanocomposite catalysts exhibited relatively stable propylene oxide (PO) production with small amounts of propanal and acetone byproducts. A catalyst prepared by grafting with trimethylsilyl groups, a Ti/Si ratio of 0.05 and very small Au nanoparticles (<2 nm), showed the highest catalytic activity. The improved performance appears to be related to the interaction of very small Au nanoparticles in close contact with very small sized TiO 2 domains in combination with the hydrophobicity of the fully open mesopores. The results demonstrate the possibility to improve the catalytic performance of Au–Ti catalysts through rational catalyst design.

Catalytic Transfer Hydrogenolysis of 2-Phenyl-2-Propanol with Pd/C and Formic Acid

The catalytic transfer hydrogenolysis of 2-phenyl-2-propanol was studied over Pd/C catalyst, using formic acid and formate salts as hydrogen donors. The Pd/C catalyst was characterized by powder X-ray diffraction (XRD), inductively coupled plasma (ICP), N2 adsorption/desorption and transmission electron microscopy (TEM). The effects of hydrogen donor, molar ratio of formic acid to 2-phenyl-2-propanol and water content were evaluated. Under mild reaction conditions (80 °C, 2h), 2-phenyl-2-propanol can be hydrogenolyzed to isopropylbenzene with very high selectivity (96.5%) and high conversion (92.8%) in the presence of Pd/C and formic acid. From the viewpoint of environmental friendly principles, this study may open the way to a new approach for the production of propylene oxide.

Effect of gold oxidation state on the epoxidation and hydrogenation of propylene on Au/TS-1

Gold nanoparticles on titanium oxide and titania-silica supports are active for the formation of propylene oxide by the oxidation of propylene with hydrogen and oxygen mixtures. Cyanide treatment of gold supported on titanosilicate zeolite supports (Au/TS-1) yielded unexpected results. Catalysts treated with weak solutions of sodium cyanide resulted in preferential removal of small gold particles, while catalysts treated with strong solutions resulted in dissolution of the gold and re-precipitation as gold (+1) cyanide. X-ray absorption spectroscopy demonstrated that catalysts that produce propylene oxide in the presence of hydrogen and oxygen mixtures had supported gold (+3) oxide nanoparticles of 3 nm size after synthesis, which were reduced to gold metal at reaction conditions. Samples treated with strong solutions of sodium cyanide resulted in supported gold (+1) cyanide particles of large size, 9–11 nm. These particles did not produce propylene oxide but, surprisingly, showed high selectivity toward propylene hydrogenation. Increasing gold (+1) cyanide particle size resulted in a decrease in hydrogenation activity.

New Catalytic Materials for the Direct Epoxidation of Propylene by Molecular Oxygen

AbstractThe direct vapor‐phase production of propylene oxide (PO) from propylene and molecular oxygen without the use of a co‐reactant remains a challenging problem in industrial catalysis, in spite of several decades of research. Herein, the discovery of a new class of silica‐supported multimetallic RuO2–CuOx–NaCl catalysts for the direct synthesis of PO from propylene and molecular oxygen is reported. This trimetallic catalyst exhibits durability and delivers PO selectivities of 40–50 % at propylene conversions of 10–20 % within 240‐270 °C and at atmospheric pressure. The best performing catalysts are characterized by powder X‐ray diffraction (PXRD) and transmission electron microscopy (TEM) and are determined to be composed of nanocrystalline domains of the three phases of RuO2, CuOx, and NaCl.

Direct gas-phase epoxidation of propylene to propylene oxide through radical reactions: A theoretical study

The gas-phase radical chain reactions which utilize O 2 as the oxidant to produce propylene oxide (PO) are investigated through theoretical calculations. The transition states and energy profiles were obtained for each path. The rate constants were also calculated. The energetics for the competing pathways indicate that PO can be formed selectively due to its relatively low activation barrier (9.3 kcal/mol) which is in a good agreement with the experimental value (11 kcal/mol) of gas-phase propylene epoxidation. The formation of the acrolein and combustion products have relatively high activation barriers and are not favored. These results also support the recent experimental findings.

Utilization of waste chloroorganic compounds

Utilization of waste chloroorganic compounds Efficient methods of utilization of waste chloroorganic compounds coming from waste water and the waste streams formed e.g. in the production of vinyl chloride by dichloroethane method and in the production of propylene oxide by chlorohydrin method have been presented. First the separation of chloroorganic wastes by the adsorption methods has been described in the article. Three valuable methods of chlorocompounds utilization have been then discussed. The first one is isomerization of 1,1,2-trichloroethane to 1,1,1-trichloroethane as the valuable product with less toxicity than a substrate. The second method is ammonolysis of waste 1,2-dichloropropane and 1,2,3-trichloropropane. The third described method is chlorolysis. This method can be used for the utilization of all types of waste chloroorganics.

Gas Phase Epoxidation of Propylene with TS-1 and in Situ H2O2 Produced by a H2/O2 Plasma

Gas phase epoxidation of propylene was performed by directly contacting propylene and gaseous H 2 O 2 on the surface of TS-1 catalyst in an integrated reactor. The gaseous H 2 O 2 was produced in situ by a H 2 /O 2 plasma. The H 2 O 2 formation rate can be enhanced by increasing the power density of the H 2 /O 2 plasma reactor. The yield and selectivity for propylene oxide (PO) can be increased by optimizing the reaction conditions and using suitable TS-1 catalysts. With a power injection of 3.5 W, flow rates of H 2 , O 2 , and propylene of 170, 8, and 18 ml/min, respectively, catalyst loading of 0.8 g, and epoxidation temperature of 110 °C, the yield and selectivity for PO and the utilization rate of H 2 O 2 were 246.9 g/(kg·h), 95.4%, and 36.1%, respectively. During the gas phase reaction, no decline of TS-1 activity was observed. ： 将 H 2 /O 2 非平衡等离子体现场产生的气态 H 2 O 2 和丙烯与耦合反应器中钛硅沸石 TS-1 直接接触, 实现了丙烯气相环氧化反应. 结果表明, 非平衡等离子体生成气态 H 2 O 2 的速率由介质阻挡放电的输入功率决定, 环氧丙烷的生成速率和选择性取决于钛硅沸石催化剂和反应条件. 在 H 2 和 O 2 进料流量分别为 170 和 8 ml/min, 介质阻挡放电输入功率为 3.5 W, 环氧化反应温度为 110 °C, 丙烯进料量为 18 ml/min, 催化剂用量为 0.8 g 的条件下, 生成环氧丙烷产率达 246.9 g/(kg·h)、环氧丙烷选择性和 H 2 O 2 有效利用率分别为 95.4% 和 36.1%, 反应 36 h 内未见催化剂失活. Gas phase propylene epoxidation was performed by contacting plasma generated gaseous H 2 O 2 and propylene over a TS-1 catalyst. The important feature is the use of gaseous H 2 O 2 for PO production.

Catalytic transfer hydrogenolysis of α-methylbenzyl alcohol using palladium catalysts and formic acid

The catalytic transfer hydrogenolysis (CTH) of α-methylbenzyl alcohol (MBA) was studied using palladium catalysts and formic acid, with the intent of developing a new approach for the production of propylene oxide (PO). The effects of support, hydrogen donor, molar ratio of HCOOH to MBA, water content, reaction temperature and catalyst recycling were evaluated. Using formic acid as hydrogen donor and Pd/C as catalyst, one can convert MBA to ethylbenzene (EB) with very high selectivity (98.8%) and high conversion (98.8%) at 80 °C for 40 min. H+ ion plays an important role, for it promotes the formation of active hydrogen species in the reaction process. A reaction mechanism was proposed to account for the results obtained in the study.

The production of propylene oxide over nanometer Au catalysts in the presence of H2 and O2

Direct gaseous-phase epoxidation of propylene over nanogold catalysts in co-presence of H2 and O2 has been extensively studied. Many researchers have made important progress in this field, and a survey of the literature published to date is presented in this article. The salient features are the nature of the nanogold particles and the Ti-based support materials.

Direct propylene epoxidation over barium-promoted Au/Ti-TUD catalysts with H 2 and O 2: Effect of Au particle size

A catalyst consisting of gold supported on a Ti-containing silicate mesoporous material (TUD) with 13-nm pores was used for the epoxidation of propylene with mixtures of H 2 and O 2. The catalyst activity was enhanced by the addition of a Ba promoter. The pH of deposition was important in controlling the gold loading and particle size. A pH of 7 gave a Au loading of 2.7 wt% and an average particle size of 2.0 nm, as determined by transmission electron microscopy, whereas a pH of 9 produced a much lower Au loading of 0.11 wt% and smaller particles of size about 0.9 nm, as estimated by X-ray absorption fine structure measurements. At 423 K and 0.1 MPa total pressure, the catalyst prepared at pH 7 gave a steady-state propylene conversion of 2.1%, a propylene oxide (PO) selectivity of 79%, and a H 2 efficiency of 3.8%, whereas that prepared at pH 9 gave a conversion of 1.4%, a PO selectivity of 99%, and a H 2 efficiency of 17%. The turnover frequency for PO production based on total gold increased on going to the sample prepared at pH 9. Thus, it is concluded that very small Au particles (about 1 nm) are the most active for epoxidation, whereas larger Au particles (about 2 nm) are less active because they promote direct H 2 oxidation to H 2O. X-ray absorption near-edge spectroscopy results indicated that at reaction conditions, the small particles had partially oxidized gold but the larger particles had metallic gold, suggesting that the smaller particles had high coverage of oxygen or oxygen-derived species.

Formation of environmentally friendly chloroorganic compounds technology by sewage and by-products utilization

Formation of environmentally friendly chloroorganic compounds technology by sewage and by-products utilization The processes presented in the study enables the separation and disposal of the chloroorganic compounds as by-products from the vinyl chloride plant by using the dichlorethane method and also from the production of propylene oxide by the chlorohydrine method. The integrated purification method of steam stripping and adsorption onto activated carbon allows a complete removal and recovery of the chloroorganic compounds from waste water. Waste distillation fraction is formed during the production of vinyl chloride. 1,1,2-trichloroethane separated from the above fraction, can be processed to vinylidene chloride and further to 1,1,1-trichloroethane. 2,3-Dichloropropene, 2-chloroallyl alcohol, 2-chloroallylamine, 2-chlorothioallyl alcohol or bis(2-chloroallylamine) can be obtained from 1,2,3-trichloropropane. In the propylene oxide plant the waste 1,2-dichloropropane is formed, which can be ammonolysed to 1,2-diaminopropane or used for the production of β-methyltaurine. Other chloroorganic compounds are subjected to chlorinolysis which results in the following compounds: perchloroethylene, tetrachloromethane, hexachloroethane, haxachlorobutadiene and hexachlorobenzene. The substitution of the milk of lime by the soda lye solution during the saponification of chlorohydrine eliminates the formation of the CaCl2 waste.

Gas-phase epoxidation of propylene through radicals generated by silica-supported molybdenum oxide

Abstract It was found that silica-supported molybdenum oxide was high effective for the epoxidation of propylene among various silica-supported metal oxides. The post-catalytic bed volume played an important role in its formation. On a MoO x /SiO 2 with 0.255 mmol/g-SiO 2 , a propylene conversion of 17.6% and a PO selectivity of 43.6% were obtained at 5 atm, 573 K and flow rates of C 3 H 6 /O 2 /He = 10/5/10 cm 3 min −1 . The characterization studies indicated that crystalline MoO 3 nano-particle species was more effective for propylene epoxidation to PO than molecularly dispersed Mo oxide species. The reaction mechanism of propylene epoxidation on MoO x /SiO 2 catalysts is hypothesized to involve gas-phase radicals generated at relatively low temperature by the dispersed molybdenum oxide species. These radicals participated in homogeneous reactions with molecular oxygen to produce propylene oxide.