A multi-station series dynamic nitrogen adsorption specific surface meter and specific surface measurement method

Abstract

The invention relates to a multistation in-series dynamic nitrogen adsorption specific surface instrument and a specific surface measuring method, the multistation in-series dynamic nitrogen adsorption specific surface instrument comprises a plurality of four-way electromagnetic valves, a plurality of U shape sample tubes, a plurality of liquid nitrogen cups, a thermal conductivity cell and a quantitative nitrogen pipeline; an adsorbing unit respectively comprises one four-way electromagnetic valve, one sample tube and one liquid nitrogen cup, the third communication port and the fourth communication port of the four-way electromagnetic valve are respectively connected with the two connecting ends of the sample tube; a plurality of adsorbing units are in in-series connection, the first communication port at the head end of the four-way electromagnetic valve in the adsorbing unit is communicated with a reference wall port of the thermal conductivity cell, the second communication port at the tail end of the four-way electromagnetic valve in the adsorbing unit is communicated with a measuring arm port of the thermal conductivity cell by the quantitative nitrogen pipeline, the second communication port close to the head end of the four-way electromagnetic valve and the first communication port close to the tail end of the four-way electromagnetic valve in two adjacent adsorbing units are communicated. The multistation in-series dynamic nitrogen adsorption specific surface instrument can greatly improve the shape of absorption and desorption peaks, improve the test precision, and shorten the test time during measuring of a small specific surface.

Description

technical field [0001] The invention relates to the technical field of dynamic nitrogen adsorption, in particular to a multi-station serial dynamic nitrogen adsorption specific surface instrument and a method for measuring the specific surface. Background technique [0002] At present, all dynamic multi-sample nitrogen adsorption instruments use a parallel gas path, that is, a mixed gas with a certain nitrogen partial pressure is divided into four paths, flows through four parallel sample tubes, and then merges back into one path to enter the thermal conductivity cell. During the test, the four sample tubes were immersed in the liquid nitrogen cup at the same time, adsorbed at the same time, and then returned from the liquid nitrogen temperature to room temperature one by one, and desorbed one by one. This method has been used to this day. There is a puzzling problem in this method, that is, when measuring the small specific surface, the desorption peak is wide and short, an...

AI Technical Summary

Problems solved by technology

There is a puzzling problem in this method, that is, when measuring a small specific surface, the desorption peak is wide and short, and the integration error of the peak area is very large, resulting in poor test accuracy of the specific surface. The usual method is to use Hot water or hot air help accelerate desorption, but the effect is limited, and it complicates the test process and is not conducive to automatic control

The study found that the occurrence of the above phenomenon is directly related to the parallel connection of the sample tubes, because when the adsorption capacity is small, the limited nitrogen desorbed from the sample tubes is diluted by the parallel undesorbed three-way gas flow, which greatly reduces the test efficiency. precision

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