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Various Cu/CeO2 nanorod catalysts with different copper contents were synthesized through a facile coprecipitation method for the hydrogenation of diethyl carbonate to methanol in a fixed‐bed reactor. The methanol yield increased upon increasing the copper loading, but large excess amounts of copper led to deactivation of the catalyst at a high liquid hourly space velocity because of aggregation of the active metal. The 20Cu/CeO2 and 30Cu/CeO2 catalysts displayed superior catalytic performance with methanol space‐time yields of 8.4 and 8.1 mmol gcat−1 h−1, respectively. The remarkably enhanced catalytic performance was mainly ascribed to a high Cu0 surface area, appropriate ratio of Cu+/Cu0, and more surface oxygen vacancies associated with Ce3+, which stemmed from a strong interaction between Cu and the CeO2 support.

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Due to the open and distributed characteristics of web service, its access control becomes a challenging problem which has not been addressed properly. In this paper, we show how semantic web technologies can be used to build a flexible access control system for web service. We follow the Role-based Access Control model and extend it with credential attributes. The access control model is represented by a semantic ontology, and specific semantic rules are constructed to implement such as dynamic roles assignment, separation of duty constraints and roles hierarchy reasoning, etc. These semantic rules can be verified and executed automatically by the reasoning engine, which can simplify the definition and enhance the interoperability of the access control policies. The basic access control architecture based on the semantic proposal for web service is presented. Finally, a prototype of the system is implemented to validate the proposal