US 6,981,426 B2
Method and apparatus to measure gas amounts adsorbed on a powder sample
Dezheng Wang, Beijing (China); Fei Wei, Beijing (China); and Jinfu Wang, Beijing (China)
Assigned to Tsinghua University, Beijing (China)
Filed on Dec. 15, 2003, as Appl. No. 10/736,829.
Claims priority of application No. 3100285 (CN), filed on Jan. 10, 2003; and application No. 200310113533 (CN), filed on Nov. 14, 2003.
Prior Publication US 2004/0134258 A1, Jul. 15, 2004
Int. Cl. G01N 15/08 (2006.01)
U.S. Cl. 73—865.5 16 Claims
OG exemplary drawing
 
1. A method for measuring gas amounts adsorbed by a powder sample in a system comprising a supply chamber of predetermined volume, a reference chamber, a temperature and temperature difference measuring means for said supply chamber and reference chamber, a pressure difference measuring means between said supply chamber and reference chamber, a sample cell of predetermined free space and containing a powder sample, a pressure measuring means for said sample cell, and an evacuating means, the method comprising the steps of:
(a) evacuating said supply chamber said reference chamber, and said sample cell;
(b) providing said powder sample a surrounding of a substantially constant known temperature;
(c) isolating said sample cell, said supply chamber, and said reference chamber from said evacuating means and isolating said sample cell from said supply chamber and said reference chamber;
(d) using a gas supply to supply gas to said supply chamber and said reference chamber, then isolating said supply chamber and said reference chamber from said gas supply by valving means;
(e) isolating said supply chamber from said reference chamber by valving means, waiting for the pressure to stabilize in both chambers, then measuring the pressure difference and temperature difference between them and the temperatures thereof;
(f) supplying gas from said supply chamber to said sample cell using a gas flow control means;
(g) measuring the pressure difference and temperature difference between said reference chamber and said supply chamber and the temperatures thereof, and using said pressure difference, temperature difference, and temperatures, and the volume of said supply chamber, calculating the amount of gas that flowed out from said supply chamber;
(h) measuring the pressure in said sample cell and using said pressure and the free space and temperature of said sample cell, calculating the amount of gas added to the free space in said sample cell;
(i) calculating by the arithmetic difference of the gas amounts in steps (g) and (h) the gas amount adsorbed by said powder sample to get the data point of adsorbed amount at this pressure in said sample cell; and
(j) repeating steps (f) to (i) until the pressure in said sample cell has increased to the required pressure, whereby obtaining data points of adsorbed amount at the increasing pressures in said sample cell.