73results about How to "Improve gas selectivity" patented technology

A gas detection method capable of solving the problem with respect to the operation at normal temperature that was impossible so far in the existent catalyst type sensor and detection with high sensitivity that was impossible by the light absorption type sensor. A multi-layered film formed of a first layer adsorbing a specified gas and a second layer having less adsorption are utilized as a detection film, and the detection film is disposed in the direction perpendicular to the optical channel and optically detects the change of stress caused in the detection film by gas adsorption as coupling loss. Alternatively, the stress generated in the detection film caused by gas adsorption is electrically detected by a piezoelectric element or capacitance element.

The invention provides a metal organic framework material used for absorbing and separating CO2 and a preparation method thereof. The metal organic framework material is a rigid metal carboxyl compound cluster-like structure which is formed by transition metal ions and multidentate organic ligands through covalent bonds and intermolecular forces. An amine polymer is modified on the metal organic framework material; and the metal organic framework material used for absorbing and separating the CO2 has a specific surface area of 1,000 to 1,200 m<2>/g, and a pore volume of 0.4 to 0.6 cm<3>/g. The preparation method comprises the following steps of: respectively dissolving the nitrate, the chloride or the carbonate of copper or zinc and 1,3,5-trimesic acid together in a stoichiometric ratio in water or an organic solvent; mixing uniformly and sufficiently to react to obtain a BTC bridged complex crystal; and applying a product obtained by reacting an obtained BTC bridged complex crystal with the solution of polyethyleneimine to the metal organic framework material used for absorbing and separating the CO2. The material can realize selective absorption of a gas under a low pressure.

The invention discloses application of a two-dimensional MXene membrane in gas separation. The application comprises the following steps: (1) placing the two-dimensional MXene membrane in a gas separation unit, and then, introducing a gas mixture required to be separated from a feed side; (2) introducing purge gas from a purge side; (3) introducing the purge gas to gas chromatography for detecting. The MXene membrane disclosed by the invention has ultrahigh H2 transmittance, ultrahigh H2/CO2, H2/N2, H2/CH4, H2/C3H6 and H2/C3H8 separation selectivity and excellent mechanical properties; a preparation method of the two-dimensional MXene membrane is simple and easy in operation, low in energy consumption, low in cost and high in repeatability and is applicable to large-scale industrial production.

The invention discloses a two-dimensional transition metal sulfide gas sensor based on an antenna structure, and preparation thereof. The gas sensor comprises a two-dimensional transition metal sulfide TMDCs film which is patterned into two connected parts of a conductive channel and an antenna structure, wherein the surface of the conductive channel is covered with a passivation layer; the antenna structure is used for adsorbing the gas to be tested as a gas sensitive layer; when molecules of the gas to be tested are adsorbed on the surface of the antenna structure and are performed with charge transfer, the concentration of carriers in the antenna structure changes to form a concentration gradient and induce the diffusion of the carriers, so that the concentration of the carriers in theconductive channel changes, and finally the resistance of the conductive channel is changed, thereby realizing the sensing of the gas to be tested by the gas sensor. The sensor, by distinguishing thegas sensitive layer and the conductive channel into two parts on the sensor structure, not only helps to increase the stability of the sensor, but also can improve the sensitivity of the gas sensor byutilizing the gain effect of the antenna structure.

The invention belongs to the technical field of a nanometer material, and provides a nitrogen dioxide gas sensor based on a SnSe2/SnO2 heterojunction as well as a preparation process and application thereof. The nitrogen dioxide gas sensor based on the SnSe2/SnO2 heterojunction mainly consists of a gas sensitive material and a heating base plate, wherein the gas sensitive material is coated on thesurface of the heating base plate; the coating thickness is 1 mum to 100 mum; the gas sensitive material is a heterojunction composite nanometer material formed by ingredients of tin diselenide and tin dioxide. A hot oxidization method is used for obtaining the novel heterojunction composite nanometer material; the raw materials can be conveniently obtained; the price is low; the heterojunction preparation process is simple; the scheme beings to a two-dimensional semiconductor heterojunction preparation scheme with the advantages of low equipment investment and simple technical flow process.The work temperature of nitrogen dioxide made of the tin diselenide and tin dioxide heterojunction composite nanometer material is 120 DEG C; the material and silicon base microelectron phase integration can be realized.

The invention belongs to the technical field of sensors and provides a light-excited formaldehyde gas sensor and a preparation process thereof. The sensor comprises a light source, a gas-sensitive material and a substrate, wherein the gas-sensitive material is uniformly coated on the surface of the substrate; the component of the gas-sensitive material is a hollow microsphere zinc oxide and stannic oxide heterojunction composite nanometer material; the coating thickness of the gas-sensitive material is 1-100 microns; the service condition is that LED lamp bead irritation is performed at the band of 365nm. The formaldehyde sensor disclosed by the invention is high in response of formaldehyde gas, and also has the characteristics of being excellent in selectivity, sensitivity and stability and capable of working at a room temperature.

The present invention relates to char molecule sieve membrane and its method especially the cannular backstop char sieve membrane. It is a new Nami material -char sieve membrane filled Nami material in char sieve membrane. The preparation method is adding Nami material in no water ethanol of bakelite colophony. Nami materials are Nami nickel, Nami NaA molecule, Nami titanium dioxide. The ultrasonic makes Nano material decentralize in the membrane liquid and dip cannular backstop. Nami material has different adsorption ability to some gas. According this, char molecule can permeate or remain some gas. So it can increase or decrease the selectivity of the gas to other gas.

The invention discloses a resistance-type nitrogen dioxide gas sensor, and an apparatus manufactured with the sensor. The sensor comprises a gas-sensitive material layer with tungsten oxide as a main gas-sensitive material, and gold conductive electrode plates arranged with an interdigitated structure, wherein the gold conductive electrode plates contact the gas-sensitive material layer. The conductive electrode plates are printed on an alumina planar medium substrate. The back side of the medium substrate is provided with a platinum heating resistor. The sensor is arranged on a pedestal with a small hole. A cap with a ventilating central hole is covered on the pedestal. Platinum conductors are respectively led out from the platinum heating resistor and the interdigitated gold conductive electrodes. The conductors led out from the platinum heating resistor are connected with a heating controlling circuit, and the conductors led out from the interdigitated gold conductive electrodes are connected with a resistance calculating circuit. The apparatus provided by the invention has a simple structure, and employs a novel gas-sensitive material. With the apparatus, an accuracy of nitrogen dioxide volume concentration detection can be improved to a PPB (parts per billion) grade. The apparatus has advantages of good gas selectivity and short reaction time.

PCT No. PCT/JP97/03318 Sec. 371 Date Apr. 15, 1999 Sec. 102(e) Date Apr. 15, 1999 PCT Filed Sep. 19, 1997 PCT Pub. No. WO98/12548 PCT Pub. Date Mar. 26, 1998Gas sensor materials composed of carbon mixture or metal-containing carbon mixture obtained as evaporated matter by arc discharge which occurs by passing an alternating current or a direct current with electric current density of 0.8 to 3.5 A/mm2 on discharge surfaces of carbon electrodes or metal-containing carbon electrodes in an inert gas under a pressure of 0.1 to 600 torr.

The invention discloses a high selectivity composite gas sensitive material used for detection of acetic acid gas in the air, and belongs to the technical field of gas sensitive material. The high selectivity composite gas sensitive material is C3N4-ZnO, the mass amount of C3N4 accounts for 5 to 20% of the total material mass; a side-heating gas-sensitive sensor is prepared from the high selectivity composite gas sensitive material, at 300 DEG C working temperature, the sensitivity on 0.1ppm acetic acid ranges from 1.2 to 1.4, the sensitivity on 1000ppm acetic acid ranges from 290 to 350, thesensitivity on 1000ppm acetone, formaldehyde, ethanol, acetaldehyde, and ammonia gas is lower than 31, it is shown that C3N4 is capable of increasing the sensitivity of zinc oxide on acetic acid gas,and increasing gas sensitive selectivity of zinc oxide on acetic acid gas, so that rapid detection of the concentration of acetic acid in the air is realized, and influences of acetone, formaldehyde,ethanol, acetaldehyde, and ammonia gas are eliminated.

A multi-component gas sensor designed by the present invention includes an electric control unit, a heating unit, a Pt10 heater and a metal oxide sensitive element are connected to the electric control unit, the heating unit is connected with the Pt10 heater, and the metal oxide The sensitive element is laid on the ceramic heating base, and the ceramic heating base is attached to the Pt10 heater, and there are multiple metal sensitive elements. In this structure, Pt10 is used as the main part of the heater. As a thermistor, it can feed back its heating temperature value in real time through its resistance value, and then detect various components of the measured gas through the metal oxide sensitive element.

The invention discloses a preparation method of a PAA/AgNPs composite flexible ammonia gas sensor. The method is characterized in that a sensitive material is prepared into an ink form suitable for being printed by a common ink-jet printer, the thickness and the shape of a deposited ammonia sensitive material layer can be conveniently controlled through an ink-jet printing method, the ammonia gassensor with good performance is prepared, and the ammonia sensitive material can be deposited as required through the ink-jet printing mode, the waste of raw materials can be effectively reduced, themanufacturing cost of the sensor is reduced, meanwhile, the large-scale manufacturing of the sensor is facilitated, and the industrial production is facilitated. According to the method, the process is simple, the production cost is low, the prepared ammonia gas sensor has relatively good response to ammonia gas at different concentrations at room temperature, the detecting range is wide, the response time is short, the stability is high, the gas selectivity is good, the ammonia gas sensor is suitable for high-sensitivity detection of ammonia gas at room temperature, good in flexibility and low in working temperature and can be applied to detection of ammonia gas around a human body by combining a wearable device.

The invention discloses a graphene-ZnGa2O4 compound gas-sensitive material with high selectivity on a formaldehyde gas, and belongs to the technical field of gas-sensitive materials. The gas-sensitivematerial is prepared from graphene-ZnGa2O4, wherein the graphene is 0.08-0.20 percent of total mass of the material. A heater type gas-sensitive sensor prepared by using the material as a sensitive material has the lowest detection limit on formaldehyde being 1ppm, the sensitivity on 1ppm formaldehyde be 1.1-1.2, the sensitivity on 1000ppm formaldehyde being 29-33 and the response time and recovery time on 1-1000ppm formaldehyde being not more than 21 seconds and 25 seconds ; and the material has high gas-sensitive selectivity since the sensitivity on 1000ppm acetone, 1000ppm trimethylamine,1000ppm acetaldehyde, 1000ppm ammonia and the like is respectively less than 2.5 at the same working temperature.

Disclosed are a tetra-beta-carboxyl phenoxy metal phthalocyanine/graphene composite material and a method. Graphene is easy to agglomerate and has relative inert surface and poor dispersity, so that defects of poor selectivity and recovery capability, low sensitivity and the like occur when graphene is used as a gas-sensitive material. Further application of a phthalocyanine complex is hindered due to an overhigh resistance value in practical application. The effect between the phthalocyanine complex and graphene is still unclear, and the distribution of the phthalocyanine complex on the surface of graphene is still not uniform. The compositions of the composite material comprise the following components: 0.85%-1.69% of tetra-beta-carboxyl phenoxy metal phthalocyanine, 0.40%-0.56% of graphene, 80.1%-83.1% of N, N-dimethylformamide, 2.61%-3.05% of hydrazine aqueous solution, and 15.2%-17.1% of ammonia water, wherein the percentage is weight percentage. The composite material is appliedto gas sensitive materials.

The invention discloses a method for adding a gas selection function of a multifunctional gas sensor and the gas sensor. The method for adding the gas selection function of the multifunctional gas sensitive sensor comprises the step of forming a nano noble metal particle modification layer on the surface of a semiconductor gas sensitive material layer of a probe of the gas sensitive sensor, so that the single probe of the gas sensitive sensor can realize selective detection on at least three gases in a working temperature range of 0-400 DEG C. According to the method for adding the gas selection function of the multifunctional gas sensitive sensor, the surface of the semiconductor gas sensitive material layer is modified by using the nano noble metal particles, so that the gas selectivity of the gas sensitive sensor is improved, the types of selected gases are expanded, and selective detection of at least three gases within the working temperature range of 0-400 DEG C can be realized; and a new scheme and a new way are provided for preparing the multifunctional gas sensitive sensor with more gas selection functions.

The invention relates to a preparation method of a sensitive material with specificity to formaldehyde gas. The method comprises the following steps: mixing a graphene oxide suspension with a solutioncontaining citric acid, glucose and SnCl2.2H2O, and adding urea and ammonia water to obtain a mixed solution; and carrying out microwave hydrothermal reaction on the mixed solution in a microwave/ultraviolet/ultrasonic three-in-one reaction instrument in a pressure control mode, and carrying out ultrasonic treatment; and then obtaining a formaldehyde gas sensitive material after microwave hydrothermal reaction. According to the invention, the SnO2 and NG are compounded and the concentrations and distribution states of pyridine nitrogen, graphite nitrogen and pyrrole nitrogen in NG are controlled by adjusting reaction medium compositions and the microwave hydrothermal preparation process, so that specific binding of formaldehyde molecules and the composite material is facilitated and thusa strong response mechanism is generated. With the heterojunction formed by SnO2 and NG, the carrier separation and transferring are promoted, the sensitivity and the response speed of the material are effectively improved, and the prepared composite material has high selectivity to formaldehyde gas.