Synthesis of a Novel Heterogeneous Strong Acid Catalyst from p-Toluenesulfonic Acid (PTSA) and its Catalytic Activities
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Synthesis of a Novel Heterogeneous Strong Acid Catalyst from p-Toluenesulfonic Acid (PTSA) and its Catalytic Activities Xuezheng Liang Æ Shan Gao Æ Guozhen Gong Æ Youfei Wang Æ Jian-Guo Yang
Received: 14 February 2008 / Accepted: 12 March 2008 / Published online: 14 May 2008 Ó Springer Science+Business Media, LLC 2008
Abstract A novel heterogeneous strong acid catalyst has been synthesized through the copolymerization of p-toluenesulfonic acid and paraformaldehyde with sulfuric acid as catalyst. The novel catalyst owns the strong acidity as much as 4.0 mmol/g, while Nafion and Amberlyst-15 only has the acidity of about 0.8 mmol/g. Furthermore, the catalyst possesses the advantages of the high thermal stability (200 °C) and low cost for the simple synthetic procedure. The catalytic activities of the novel catalyst were taken through esterification of acetic acid and ethanol and acetalization of benzolaldehyde and 1,2-ethandiol. The results showed that the novel catalyst showed much higher activities than the Amberlyst-15 and owned even the comparative activity to sulfuric acid, which made the catalyst hold great potential for the replacement of the traditional homogeneous catalyst for the green process. Keywords Novel heterogeneous strong acid catalyst High activity High stability Green process
1 Introduction Acid-catalyzed reactions are one of the most important reactions in chemical industry and the catalysts play the key role during the processes. Over 15 million tons of sulfuric acid is annually consumed as ‘‘an unrecyclable catalyst’’—which requires costly and inefficient separa-
X. Liang S. Gao G. Gong Y. Wang J.-G. Yang (&) Shanghai Key Laboratory of Green Chemistry and Chemical Process, East China Normal University, Shanghai 200062, China e-mail: [email protected]
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tion of the catalyst from homogeneous reaction mixtures—for the production of industrially important chemicals, thus resulting in a huge waste of energy and large quantities of waste products [1–8]. From the view of green process, many heterogeneous catalysts such as organic acid/inorganic solid oxide hybrids and strong acidic cation-exchangeable resins were used for the replacement of the catalyst [9–13]. Nafion is one of the most famous heterogeneous acid catalysts from Du Pont. Nafion owned excellent heat-resistant properties which can be used at 200 °C. But the catalyst owned low acidity of about 0.8 mmol/g. Moreover, most of the acid sites were inside the catalyst that cannot take effect during the reaction due to its low BET surface (0.02 m2/g). Also the high price made the catalyst impossible for the wider application in chemical industry [14–16]. Amberlyst-15 is another famous acidic cation-exchangeable resin commercial available. The catalyst owned a higher acidity and BET surface (45 m2/g) than that of Nafion. However, the low thermal instability (\ 120 °C) limited its application area [17]. So there is a great desire for the heterogeneous acid catalysts that possessed both the high acidity and stability. In or
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