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The creation of a catalytic method that possesses high activity and effective reusability for the oxidative cleavage of vegetable oils and their derivatives to prepare bio-based oxo-chemicals is a challenge. This work introduces a “release and capture” catalytic system consisting of H2O2, WO3 and mesoporous SnO2. This system was intended to promote catalyst reusability in the oxidative cleavage of methyl 9,10-epoxystearate (ME) to the corresponding aldehydes. No organic solvent was used in the reaction. The reaction temperature, molar ratio of ME/WO3/H2O2, and reaction time were optimized to 70 °C, 1/0.017/1.3, and 20 min, respectively. Under these conditions, complete ME conversion and 80% aldehyde yield were obtained. The hot filtration experiment and ICP-MS analysis confirmed the leaching of tungsten. Mesoporous SnO2 did not affect the ME conversion and aldehyde yield, but effectively adsorbed the leached tungsten. The catalyst in this system showed no significant decrease in activity after being reused ten times.

The performance of GPS based frequency standard depends on the accuracy and stability of the time interval measurement. Based on the XILINX Spartan-3 FPGA, this paper mainly describes a time interval measurement system which is controlled by the PicoBlaze soft core embedded processor and is suitable for the frequency calibration of GPS based frequency standard. Besides receiving the measurement data and the time information of GPS module, PicoBlaze is used to supervise the system status, which ensures the whole system work effectually. The system has been implemented using XC3S200 device and the test show that the whole system works perfectly and meets the requirement of GPS based frequency standard.