Acid–base bifunctional catalysis: An industrial viewpoint

Catalytic processes developed and commercialized in Japan during 1994–2009 are reviewed and classified into 6 industrial areas: petroleum and energy, bulk chemicals, polymers, fine chemicals, auto exhaust catalysts, and environmental catalysts. They have contributed to overcome a rise in oil price as well as to promote Green Sustainable Chemistry. While these technologies made significant contributions to respond to social issues or commercial demands, continuous efforts for development of these processes greatly promoted the catalytic science and technologies including catalytic materials, concepts, mechanism and surface science of catalysis.

Recent progress in catalytic technology in Japan – II (1994–2009)

Without using any acid or base catalyst, complexing agent or zirconium alkoxides, ZrO2–SiO2 mixed oxide with the ZrO2 content of 50 mol% was prepared by combination of sol–gel and alcohol-aqueous heating method using zirconyl nitrate and tetraethoxysilane as starting materials. The structural and surface acidic properties were characterized by FT-IR, XRD, NH3-TPD and pyridine adsorption FTIR. Compared with another mixed oxide with the same ZrO2 content prepared by mechanical grinding, the obtained ZrO2–SiO2 mixed oxide was homogeneously mixed in molecular level. The existed Zr–O–Si hetero-linkages strongly retarded the ZrO2 particle growth. The obtained mixed oxide maintained amorphous phase until it was calcined at 1,173 K for 3 h when crystallization of tetragonal zirconia took place. NH3-TPD and pyridine adsorption FTIR showed that both Bronsted and Lewis acidity were largely developed in the mixed oxide and most of the acidic sites belonged to the medium acidity. Because of the existence of abundant medium acidity, the mixed oxide showed catalytic activity for tetrahydrofuran polymerization. Furthermore, the produced poly tetramethylene ether glycol had moderate average molecular weight around 2,000. Neither the pure oxides nor the mixed oxide prepared by the mechanical grinding presented catalytic activity for this reaction.

Preparation of ZrO2–SiO2 mixed oxide by combination of sol–gel and alcohol-aqueous heating method and its application in tetrahydrofuran polymerization

Lignin has enormous potential for use as a raw material in the polymer industry. However, lignin has not been utilized as a raw material despite its many advantages because of its brittleness and difficulty of processing. Chemical modification of lignin is an important area of lignin research. In this study, two types of alkyl-chain-based modification agents were used. In the case of the polymeric materials blend, polymers are blended well so that the polymer solubility parameter (SP) values are close to each other. This is similar to the well-mixed combination of water and alcohol. If the SP value is very different, phase separation occurs, as in the relationship between water and oil. The two alkyl chain derivatives block the hydroxyl groups of lignin and replace them with glycoside. Moreover, they can alter the SP value of the modified lignin to make it similar to that of a synthetic polymer to enable blending. Cellulose is compatible with hemicellulose, which is coupled to lignin by ether, glycoside, and ester bonds in plant fibers. To mimic this structure, in this study, lignin was combined with an alkyl chain with a similar SP value and was used as a matrix polymer to form glycoside bonds. This relationship between lignin and the alkyl chain is similar to that between the cellulose and lignin-carbohydrate-complex (LCC). PLA-modified lignin (PLAL) and tetrahydrofuran-modified lignin (THFL) exhibited remarkable changes in the presence of an alcohol functional group. The results of 1H-NMR analysis confirm those obtained by FT-IR analysis. The results of the DSC analyses indicate that lignin and modified lignin exhibit different thermal properties. The results of the thermal and mechanical analyses of the modified lignin/PLA blends demonstrate that the characteristics of the alkyl chains used to modify lignin were well reflected in the final blends. Alkyl-chain-modified lignin that mimics LCC was observed to enhance the compatibility between the matrix polymers used in this study and modified lignin.

Effect of alkyl-chain-modified lignin in the PLA matrix

Effects of support pore size on new Cs2.5H0.5PW12O40/SiO2 catalysts for the ring-opening polymerization of tetrahydrofuran

New industrial process of PTMG catalyzed by solid acid

Polymerization of tetrahydrofuran (THF) catalyzed by solid acid in the presence of acetic anhydride was studied. Moderate Lewis acid catalyst produces PTME (PTMG-diacetate) having appropriate molecular number (Mn). Mixed oxide materials show good performance. Mass transfer study suggests the importance of pore size of the support and of the location of active sites. They affect the Mn and the polydispersity (Mw/Mn) strikingly. The commercial technology has established by utilizing these results.

Tomohiro Kawai

Papers

New industrial process of PTMG catalyzed by solid acid

New industrial process of PTMG catalyzed by solid acid supported on mesoporous material