Abstract: A method and system for preparing epoxypropane by direct epoxidation of propylene includes the steps of subjecting a mixed gas of a first feed gas and a second feed gas to a contact reaction with a catalyst under reaction conditions of propylene epoxidation to prepare epoxypropane. The first feed gas contains oxygen gas and is free or substantially free of hydrogen gas. The second feed gas contains hydrogen gas and is free or substantially free of oxygen gas. The first feed gas and/or the second feed gas contain propylene, at least one of the first feed gas and the second feed gas further contains a diluent gas. The method can be used for reducing dosage of diluent gas, preferably recycling the tail gas, thereby significantly increasing the conversion rate of propylene without compromising the service life of catalyst.

Abstract: A gas-sensitive material, a preparation method therefore and an application thereof, and a gas sensor using the gas-sensitive material are provided. The gas-sensitive material is a carbon material-metal oxide composite nanomaterial formed by compounding a carbon material and metal oxides. The content of the carbon material is 0.5˜20 wt. % and the content of the metal oxides is 80˜99.5 wt. %; the metal oxides contain tungsten oxide and one or more selected from tin oxide, iron oxide, titanium oxide, copper oxide, molybdenum oxide, and zinc oxide; the metal oxides are formed on the carbon material in the form of nanowires, and the nanowires are tungsten oxide-doped nanowires. The gas-sensitive material has reduced resistance, is capable of responding to various gases at a reduced working temperature.

Abstract: A gas sensor has a sensing structure that is used for generating, for a variety of gases, multiple corresponding electric signals. It has a plurality of measuring electrodes and a gas-sensitive film coating the measuring electrodes; and a micro-heating structure that is used for providing different heating temperatures for the sensing structure, and a silicon-based substrate and a heating layer disposed on the silicon-based substrate. The heating layer integrates heating electrodes of different sizes or different layouts to form a plurality of heating regions of different temperatures, and the plurality of measuring electrodes are respectively disposed in the corresponding heating regions. By integrating heating electrodes of different sizes or different layouts on a single micro-heating structure to form heating regions of different temperatures, a complex atmosphere detection function of a variety of sensing materials at different temperatures is achieved.