Young-Kwon Park

Hydrocarbon synthesis through CO2 hydrogenation over CuZnOZrO2/zeolite hybrid catalysts

Abstract Direct syntheses of hydrocarbons from CO 2 hydrogenation were investigated over hybrid catalysts consisting of methanol synthesis catalyst (CuZnOZrO 2 ) and zeolites (MFI and SAPO). The yield of hydrocarbons was strongly depending upon the amount of zeolites acid sites as measured by NH 3 TPD, while the product distributions were hardly affected by the change of acidity. The main product was ethane in the case of MFI hybrid catalyst and C 3 or C 4 hydrocarbon in the case of SAPO hybrid catalyst. This difference in product distribution was attributed to different mechanism of hydrocarbon formation. Investigation based on the ethene co-reaction suggested that the consecutive mechanism operated for HZSM-5 and the carbon pool mechanism for SAPO.

Selective synthesis of C3–C4 hydrocarbons through carbon dioxide hydrogenation on hybrid catalysts composed of a methanol synthesis catalyst and SAPO

Abstract Direct synthesis of hydrocarbons through carbon dioxide hydrogenation was investigated over hybrid catalysts composed of methanol synthesis catalysts (Cu/ZnO/ZrO 2 and Cu/ZnO/Al 2 O 3 ) and molecular sieves (H-ZSM-5, SAPO-5 and SAPO-44). It was found that the hybrid catalyst with SAPO-5 or SAPO-44 was effective for the synthesis of C 2+ hydrocarbons. The high hydrocarbon yield appears to be due to the abundance of weak- and medium-strength acid sites in SAPO, which could be evidenced through temperature-programmed desorption of ammonia. The product distribution of hydrocarbon products was influenced by the acidity as well as the pore size of the molecular sieves. The selectivity to isobutane was the highest on the hybrid catalysts with SAPO-5. Propane was the main product on the hybrid catalyst with SAPO-44. Carbon dioxide conversion increased with reaction temperature, but a maximum yield of C 2+ hydrocarbon was obtained at 340°C. An increase in contact time lowered the carbon monoxide formation and increased the hydrocarbon formation. Addition of carbon monoxide or ethene to the feed increased the hydrocarbon yield. The reaction pathway to hydrocarbons is thought to be composed of methanol synthesis from carbon dioxide and hydrogen, methanol/dimethyl ether to lower alkene, alkene oligomerization, isomerization and hydrogenation to alkane.

A Study on Methanol Synthesis through CO2 Hydrogenation over Copper-Based Catalysts

In CO2 hydrogenation over Cu/ZrO2 based catalysts, the methanol formation activity could be correlated with copper dispersion. The reaction intermediates of methanol synthesis were carbonate, formate, formaldehyde and/or methoxy, and the rate determining step for methanol synthesis seems to be the conversion of formate into formaldehyde or methoxy.

Effects of CO2 addition on the aromatization of propane over metal-loaded ZSM-5 catalysts

The catalytic reduction of CO 2 accompanying the aromatization of propane is a new type of catalytic reaction for the utilization of CO 2 . CO 2 is reduced into CO by hydrocarbon, and hydrocarbon (propane) is converted into more valuable products. This type of reaction is more economical than the hydrogenation of CO 2 , since propane is much cheaper than hydrogen. The combined conversion of propane and CO 2 was investigated by using metal-loaded ZSM-5 catalysts, which were characterized by temperature-programmed desorption, X-ray diffraction, thermogravimetric analysis and BET analysis. Reduction of CO 2 by propane resulted in higher conversion of CO 2 and higher CO yield than that by hydrogen. The incorporation of metal ions, such as Zn 2+ , Cr 3+ , Fe 3+ and Ni 2+ , into HZSM-5 enhanced the catalytic activity for CO 2 reduction. The addition of CO 2 was found to suppress the coke deposition during the aromatization of propane.

Aromatization of n-pentane over Ni-ZSM-5 catalysts

Aromatization of n-pentane was investigated over a nickel ion-exchanged H-ZSM-5 catalyst (Ni-ZSM-5). It was found that the Ni-ZSM-5 catalyst was highly active and selective to aromatics, being equivalent to Ga-ZSM-5 or Zn-ZSM-5. The high aromatic yield was attributed to the increase in the number of Lewis acid sites as well as the active role of Ni2+ ions for converting the olefin intermediates to aromatics