Kazuhisa Murata

Catalytic Cracking of Naphtha to Light Olefins

A catalytic process that produces light olefins from naphtha was developed to improve the yield of the conventional steam cracker. In laboratory-scale tests, a newly developed zeolite-based catalyst at a reaction temperature of 650 °C produced an ethylene-plus-propylene yield of about 60%, which is about 10% higher than the conventional process operated at around 820 °C. A feasibility study carried out for a catalytic cracking process using the developed catalyst, that cracks 3 000 tons-naphtha/day, indicated an energy saving of about 20% compared with the conventional process.

Steam Reforming of Methanol Over Cu/CeO2 Catalysts Studied in Comparison with Cu/ZnO and Cu/Zn(Al)O Catalysts

A series of Ce1-xCuxO2-δ mixed oxides were synthesized using a co-precipitation method and tested as catalysts for the steam reforming of methanol. XRD patterns of the Ce1-xCuxO2-δ mixed oxides indicated that Cu2+ ions were dissolved in CeO2 lattices to form a solid solution by calcination at 773K when x < 0.2. A TPR (temperature-programmed reduction) investigation showed that the CeO2 promotes the reduction of the Cu2+ species. Two reduction peaks were observed in the TPR profiles, which suggested that there were two different Cu2+ species in the Ce1-xCuxO2-δ mixed oxides. The TPR peak at low temperature is attributed to the bulk Cu2+ species which dissolved into the CeO2 lattices, and the peak at high temperature is due to the CuO species dispersed on the surface of CeO2. The Ce1-xCuxO2-δ mixed oxides were reduced to form Cu/CeO2 catalysts for steam reforming of methanol, and were compared with Cu/ZnO, Cu/Zn(Al)O and Cu/AL2O3 catalysts. All the Cu-containing catalysts tested in this study showed high selectivities to CO2 (over 97%) and H2. A 3.8wt% Cu/CeO2 catalyst showed a conversion of 53.9% for the steam reforming of methanol at 513K (W/F = 4.9 g h mol-1), which was higher than that over Cu/ZnO (37.9%), Cu/Zn(Al)O (32.3%) and Cu/AL2O3 (11.2%) with the same Cu loading under the same reaction conditions. It is likely that the high activity of the Cu/CeO2 catalysts may be due to the highly dispersed Cu metal particles and the strong metalsupport interaction between the Cu metal and CeO2 support. Slow deactivations were observed over the 3.8wt% Cu/CeO2 catalyst at 493 and 513K. The activity of the deactivated catalysts can be regenerated by calcination in air at 773K followed by reduction in H2 at 673K, which indicated that a carbonaceous deposit on the catalyst surface caused the catalyst deactivation. Using the TPO (temperature-programmed oxidation) method, the amounts of coke on the 3.8wt% Cu/CeO2 catalyst were 0.8wt% at 493K and 1.7wt% at 513K after 24h on stream.

Production of olefins from ethanol by Fe-supported zeolite catalysts

Ethanol conversion to C3+ olefins over Fe/H-ZSM-5 catalysts was investigated. Fe is a non-toxic and cheap metal. C3+ olefins are useful not only as fuels but also chemicals. Fe catalysts are fully effective even in the presence of water in EtOH. Therefore, there is no need to remove water from water-containing ethanol, such as bio-ethanol. The initial selectivity of C3+ olefins was not affected by the kind of Fe source and calcination temperature significantly, except in the case of iron phosphate used as the iron source, which showed low C3+ olefins selectivity. In general, the selectivity of C3+ olefins was slightly decreased with time-on-stream. As causes of catalytic deactivation, carbon deposition on the catalyst and framework collapse of the zeolite support can be considered. However, in the cases of Fe2(SO4)3- and FeCl3-derived catalysts, calcined at 700 °C, the decrease in C3+ olefins selectivity could be suppressed. In general, selectivity of aromatics was decreased and selectivity of ethylene was increased with time-on-stream. Used catalyst can be regenerated by air treatment at 500 °C, but the degree of regeneration was dependent on the kind of iron starting materials and the calcination temperature. An FeCl3-based catalyst, calcined at 700 °C, and catalysts calcined at 900 °C (irrespective of iron source) can be almost completely regenerated, while Fe(NO3)3- or Fe2(SO4)3-based catalyst, calcined at 700 °C, cannot be completely regenerated by this treatment.

Oxidative dehydrogenation of ethane by carbon dioxide over sulfate‐modified Cr2O3/SiO2 catalysts

The oxidative dehydrogenation of ethane into ethylene by carbon dioxide over unsupported Cr2O3, Cr2O3/SiO2 and a series of Cr2O3/SiO2 catalysts modified by sulfate was investigated. The results show that Cr2O3/SiO2 is an effective catalyst for dehydrogenation of ethane and CO2 in the feed promotes the catalytic activity. Sulfation of silica will influence the catalytic behavior of Cr2O3/SiO2 in dehydrogenation of ethane with carbon dioxide depending on the amount of sulfate. Cr2O3/6 wt% SO42-–SiO2 catalysts exhibit an excellent performance for this reaction, giving an ethylene yield of 55% at 67% ethane conversion at 650°C. Characterizations indicate that addition of sulfate changes the bulk and surface properties of Cr2O3/SiO2, promoting the reduction of Cr6+ to Cr3+ and favoring the catalytic conversion.

Dehydrogenation of Ethylbenzene to Styrene in the Presence of CO2 over Calcined Hydrotalcite-Like Compounds as Catalysts

Calcined hydrotalcite-like compounds were effective catalysts for the dehydrogenation of ethylbenzene in the presence of CO2 as an oxidant. X-ray diffraction patterns suggested that the catalyst components are distributed uniformly. The activity (areal rate) of Fe(1)/Al(2)/Zn(6) oxide catalyst (molar ratios in parentheses) was the highest among the catalysts tested.

Cracking of n-Butane Over Alkaline Earth-Containing HZSM-5 Catalysts

The effect of alkaline earth modification on HZSM-5 was investigated by catalytic cracking of n-butane under non-oxidative and oxidative conditions. The yields of aromatic products were low compared with that obtained using the non-modified HZSM-5, and higher yields of ethylene and propylene were observed with Mg-, Ca-, and Ba-ZSM-5. The NH3-TPD spectra of these catalysts show that the strong acid sites were transformed to weak acid sites. The dehydrogenation cracking was considered to occur at the acid sites modified with the alkaline earth elements because the ethylene/ethane ratio and the C2/other products ratio were high using the alkaline earth-containing HZSM-5. It is suggested that the suppression of hydrogen transfer reaction and the stimulation of dehydrogenation cracking were the major cause of the improvement of olefin yield in the cracking.

Carbonylations with CO/H2O and CO/H2 catalyzed by Co2(CO)8-1,2-bis(diphenylphosphino)ethane complexes

Abstract Carbonylations (hydroformylation and hydrocarbonylation) catalyzed by the Co2(CO)8-1,2-bis(diphenylphosphino)ethane (dpe) system under CO/H2O and CO/H2 are discussed. In the hydroformylation using CO/H2 as well as hydroformylation and hydrocarbonylation using CO/H2O, the most active catalyst was formed with a ca. 1:1 ratio of phosphorus to cobalt (= dpe/Co2(CO)8). Monophosphines such as PPh3are less effective ligands for these carbonylations using CO/H2O than is dpe. The order of reactivity of the catalysts for hydroformylation using CO/H2 was Co2(CO)8-dpe > Co2(CO)8 > Co2(CO)8-PPh3. Evidence suggests that the active species which catalyses the carbonylations with CO/H2O participates in the hydroformylation with CO/H2. Comprehensive schemes of these carbonylations, which were performed under two different sets of conditions, are proposed. This is the first report that the catalyst is effective for aminomethylation using CO/H2O; N-butylmorpholines were produced in 89% yield from the reaction of propylene with morpholine as the secondary amine.

Effect of promoters on catalytic performance of Cr/SiO2 catalysts in oxidative dehydrogenation of ethane with carbon dioxide

Several acidic and basic oxide promoted Cr/SiO2 catalysts were prepared and investigated in oxidative dehydrogenation of ethane in the presence of carbon dioxide. The effects of SO42−, WO3 and alkali metal oxides (Li2O, Na2O, and K2O) on the catalytic activity were studied. It is found that sulfation of silica produces a positive effect on ethane conversion and ethylene yield while tungstation and addition of strong basic promoters (alkali metal oxides) suppress the catalytic activity. Characterization indicates that the varying activity of the promoted catalysts can be attributed to the difference in acid/base property and redox potential.

Dehydrogenative Cracking of n-Butane over Modified HZSM-5 Catalysts

Dehydrogenative cracking reaction of n-butane was studied using HZSM-5 catalyst modified with various metal oxides. Alkaline earth (magnesium), transition metal (cobalt) and rare earth (lanthanum) elements are used for the modification. The selectivity of the products was studied at low conversion (≲20%). Methane, ethane, ethylene, propylene, butenes and butadiene were the main products. With the use of the cobalt- or magnesium-containing HZSM-5, dehydrogenative cracking was observed and the selectivity of ethylene was much larger than that of ethane. On the other hand, the selectivity of ethylene and ethane were almost the same in the reaction using the lanthanum-containing HZSM-5. It is considered that the cobalt- and magnesium-loaded sites on HZSM-5 played an important role in the dehydrogenative cracking.

Epoxidation of propylene with molecular oxygen in methanol over a peroxo-heteropoly compound immobilized on palladium exchanged HMS

The peroxo-heteropoly compound {HPO4[W(O)(O2)2]2} was synthesized on the surface of HMS by reacting HMS-PrNH(PO3H2) with [W2O3(O2)4(H2O)2]2− solution, and then palladium ions were exchanged into the channels of HMS to form a hybrid catalyst. The novel solid catalyst showed 34.1% propylene conversion and 83.2% selectivity for propylene oxide for the oxidation of propylene using molecular oxygen as an oxidant in methanol at 373 K for 6 h. Because {HPO4[W(O)(O2)2]2} was immobilized on the HMS surface by chemical bonds and palladium particles formed during the reaction were fixed in the HMS channels, the solid catalyst could be reused by a simple filtration method and the active components did not leach into the methanol medium after reaction. The selectivity for propylene oxide over the solid catalyst was similar to that over a homogeneous catalyst containing [(C6H13)4N]2{HPO4[W(O)(O2)2]2} and Pd(OAc)2, but the propylene conversion over the solid catalyst was lower than that over the homogeneous catalyst. The highest yield of propylene oxide obtained over the solid catalyst by increasing catalyst amount was similar to the highest yield of propylene oxide over the homogeneous catalyst.