Adsorption apparatus, automatic

Pore Size Distribution of Porous Systems as Determined with an Automatic Adsorption Apparatus and Digital Computer... 

A further step in the application of automatic adsorption apparatus is to run a sequence of samples without operator attention. This has been accomplished for adsorption data alone, and, in principle, is possible with complete adsorption-desorption data. 

Pore dimensions for all samples studied were calculated from the adsorption data. Adsorption/desorption isotherms were recorded using a conventional volumetric technique with nitrogen adsorbate at 77 K. The adsorption isotherms were measured with ASAP 2010 (Micromeritics) automatic gas adsorption apparatus. The specific surface areas were determined from the nitrogen adsorption isotherms using the BET method, assuming the cross section ofN2 molecule as 0.162 nm. ... 

Nitrogen and krypton physisorption measurements at 77 K and hydrogen chemisorption measurements at 293 K were carried out with a Belsorp 28SA automatic adsorption apparatus in order to obtain BET surface area and the number of surface nickel atoms, respectively. The structure of catalysts was determined by X-ray diffraction using Cu radiation. 

The water vapor [23] and nitrogen gas [24] adsorption isotherms determined by using automatic adsorption apparatus have been reported. On the other hand, the manual adsorption method for the adsorption of water vapor and nitrogen gas is discussed in Refs. 25 and 4, respectively. The amount adsorbed is determined by using a Shibata moisture and surface area apparatus. Model P-850 [Shibata Scientific Technology, Ltd., Tokyo, Japan) [25]. The amounts of water vapor and nitrogen gas adsorbed are determined by the gravimetric method [25] and volumetric method [4], respectively. 

The nitrogen adsoiption isotherms were measured volumetrically at 77 K using an automatic adsorption apparatus (Quantachrmne, Autosoib-l-MP). Each sample was outgassed at 423 K and 1 mPa for 12 h before the adsorption measurmnents. 

Other calorimeters include heat-leak calorimeters", such as of Thomas Parks (Ref 25,p 545), "automatic calorimeters such as of Andrews, Berl Stull (Ref 25,p 551) "vacum-walled calorimeter (Ref 3,p 153) "aneriod (unstirred) calorimeters" (Ref 3,pp 23,160-7), "rotating bomb calorimeters", such as of Popov, Shirokikh and of Hubbard (Ref 25,p 594) liquid-phase calorimeter" of Kistiakowsky (Ref 25,p 636), "gas calorimeter of Cutler- Hammer (Ref 18a), calorimeter for gaseous heat capacities of Waddington (Ref 15,p 802), "flow calorimeter of Junkers (Ref 15,p 805)," flow calorimeter of Osborne et al (Ref 25,p 565), "flow calorimeter of Pitzer (Ref 25,p 566), "flow calorimeter of Bennewitz Schulze (Ref 25,p 567) and "fiame calorimeter of Rossini" (Ref 25,pp 600--2). An apparatus for detn of heats of vaporization is described in Ref 25,p 615 and an "adsorption calorimeter in Ref 25,p 618... 

An offline measurement apparatus is usually not directly mounted on the reactor, but is fed with samples withdrawn from it manually or automatically. This is the typical case of chromatography, a widely used measurement device for gas and liquid composition. Both gas and liquid chromatographies are based on the separation of the sample by means of selective adsorption on a solid substrate posed in a fixed bed column, and on the detection of the change of a suitable property of the (gas or liquid) carrier, usually thermal conductivity. 

The catalyst powder was characterized by atomic absorption (chemical composition), X-ray powder diffraction (structure identification and degree of crystallinity) and nitrogen adsorption/desorption. For the latter method, an automatic Micromeretics ASAP 2000 apparatus was used, which also allowed the determination of the pore size distribution in the mesopore and macropore region (2 nm to 300 nm). 

A series of silica gels were synthesised from TEOS, selecting the experimental conditions (pH and water/TEOS ratio) in order to obtain samples with different porosity. Porous texture characterisation of these samples was done by gas adsorption (N2 and CO2 adsorption at 77 K and 273 K, respectively) (Quantachrome. Autosorb 6). The samples were degassed at 623 K under vacuum, until 10 torr. Water adsorption studies were carried out at 298 K in an automatic volumetric gas adsorption instrument (Belsorb 18). Experimental data was corrected for adsorption on inner wall of apparatus. Additionally, a blank experiment on all bulbs used showed that water adsorption on the inner surface of glass was negligible. Previous to water adsorption... 

The solids, particularly the 1.77 %-Cu-H-ZSM-5(19) and the parent H-ZSM-5, were characterized before and after steam treatments by various techniques powder X-ray diffraction (Siemens diffractometer with CuKa radiation), SEM (Hitachi S800 with a 10 nm resolution), N2 adsorption (BET and pore volume with a lahoratory-made automatic apparatus), FTIR spectroscopy (framework vibrations with KBR dilution and CO probe molecule in an in situ cell), Si and AI MAS NMR (BRUKER DSX 400). 

A further and very efficient method of purifying aqueous surfactant solution consists in a cyclic removal of the adsorption layer. The general idea is to establish an almost equilibrium adsorption layer in which the highly surface active impurity is enriched with respect to the main surfactant. If the adsorption layer is removed, the ratio of surfactant/impurity is changed (cf. Eq. (5.6)). The idea has been realised in an apparatus which automatically performs the following steps (Lunkenheimer et al. 1987a) ... 

Apparatus and Procedure. The metal films were deposited and adsorption thereon was carried out in a high-vacuum apparatus, as shown in Figure 1. The mica window was supported between two chambers that were evacuated simultaneously to prevent breakage the window was coated by evaporating metal from a heated filament in the upper chamber. The gas was then admitted to both chambers until the pressure was 1 atm. Valve 3 was closed to isolate the upper chamber, the bottom plate was removed, and the coxmter tube was positioned mder the window. After the film had been exposed 15 minutes to the gas, the solution was admitted and counting was started with an automatic coxmter-printer system. 

In continuous processes at least two adsorbers are used in parallel (adsorption, desorption). Because of the complicated operation, fully automatic apparatus is preferred (Figure 2.3.6-1). 

The BET Brunauer, Emmett, Teller) (26-28) method of-calculating speciiic surface area from an adsorption isotherm has been mainly applied to nitrogen as the adsorbate at -196 C, Innes (29) developed a rapid automatic technique for measuring the isotherm. Lippens and Hermans described suitable apparatus in detail (30, 31). Also, commercial equipment has been developed using the static equilibrium method, which does not require calibration and gives surface area by automatic digital readout (e.g., Micromeritics, Inc.). 

Recently an automatic apparatus for surface areas and pore size determination has been described [125]. The Isothermegraphe is a volumetric apparatus, with a calibrated tube, which draws complete adsorption-desorption isotherms using a piston of mercury which modifies the pressure slowly at a programmed speed. 

Anew apparatus for continuous adsorption is described. This apparatus is based on a new technique which uses proportional valves with an upstream pressure regulation. The decrease of upstream pressure is programmed at about 1 torr/min, leading to constant flow rates in the range of 0.17 to 0.2 ml(STP)/min independent of the downstream pressure. Complete nitrogen adsorption-desorption isotherms can be recorded with an automatic procedure. The main advantages of this new apparatus are simplicity, accuracy and a wide field of applications, including the study of microporous solids. 

Cellulose(CEL, Toyobo KF1500)-, pitch(PIT,Osaka gas AlO)-, and polyacrylonitrile(PAN, Tohorayon FE200)-based ACF s have been used in this study. Nonporous carbon black(NPC, Mitsubishi Kasel 32 [21]) was also used for comparison. The adsorption isotherms of N2 and Ar were statically measured by an automatic gravimetric apparatus at 77 K. The detailed description of this apparatus has been reported[15]. We obtained adsorption isotherms of more than... 

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