THE DISCONTINUITY IN THE ADSORPTION OF GASES, VAPORS, AND LIQUIDS ON SOLID SURFACES AT THE CRITICAL TEMPERATURE UNDER CRITICAL PRESSURE: SYSTEM PROPYLENE-ALUMINA

1933 ◽  
Vol 9 (3) ◽  
pp. 240-251 ◽  
Author(s):  
H. E. Morris ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Liquid State ◽  
Critical Pressure ◽  
Solid Surfaces ◽  
Pressure System ◽  
Gaseous State ◽  
Adsorbed Phase ◽  
Adsorption Processes ◽  
Adsorption Of Gases ◽  
Adsorption Curve

An apparatus and a technique for studying the adsorption of gases, vapors and liquids on solid surfaces are described. The arrangement permits investigations in the region of the critical temperature and the critical pressure. Results with the system propylene and alumina are given. Adsorption from the gas and vapor phases indicates the formation of a surface complex which is unstable at low pressure and high temperature. The density of the adsorbed phase is greater than that of the bulk phase. There is no discontinuity in adsorption processes with a change from vapor state to gaseous state. No evidence was obtained of an increase in critical temperature on the surface of the solid. Adsorption does not occur from the liquid state, and there is a marked discontinuity in the adsorption curve with a change from liquid state to gaseous state. This is probably due to a change in the forces of attraction between liquid molecules and the solid as compared with the attraction between gaseous or vapor molecules and the solid surface. If this is the case it is further evidence for the discontinuity in the region of the critical temperature, which has been previously observed in other experiments in this laboratory.

PERSISTENCE OF THE LIQUID STATE OF AGGREGATION ABOVE THE CRITICAL TEMPERATURE

1938 ◽  
Vol 16b (9) ◽  
pp. 289-302 ◽  
Author(s):  
R. L. McIntosh ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Statistical Mechanics ◽  
Liquid State ◽  
Critical Pressure ◽  
Critical Density ◽  
Small Correction ◽  
Pressure Region ◽  
The Difference ◽  
Liquid States ◽  
Made In

The data obtained by Maass and Geddes (7) on the properties of ethylene in the critical-temperature–critical-pressure region have been substantiated although it was shown that a small correction had to be applied to their absolute values of density. It was shown that at the critical density of ethylene the difference between the densities of the medium below and above the point at which the meniscus disappeared was a maximum. The conclusion of Mayer and Harrison (made in their recent papers on statistical mechanics of condensing systems (6, 10)) that, at a temperature just above that at which the meniscus disappeared, the pressure of the system remains constant over a considerable variation of mass per volume, has been corroborated. The effect of the presence of small measured quantities of air has been examined. The phenomena observed are explained on the basis that there is a difference between the gaseous and liquid states of aggregation with a structure assigned to the latter.

REVERSIBILITY IN PHYSICAL ADSORPTION

1955 ◽  
Vol 33 (2) ◽  
pp. 245-250 ◽  
Author(s):  
E. L. Pace ◽  
K. S. Dennis ◽  
S. A. Greene ◽  
E. L. Heric
Keyword(s):  
Heat Capacity ◽  
Adsorption Isotherms ◽  
Physical Adsorption ◽  
Zero Point ◽  
Solid Surfaces ◽  
Heats Of Adsorption ◽  
Calorimetric Measurements ◽  
Adsorbed Phase ◽  
Adsorption Of Gases ◽  
Calorimetric Studies

The question of reversibility and equilibrium is considered in relation to the physical adsorption of gases on finely divided solid surfaces. Conclusions are drawn from calorimetric measurements of (1) adsorption isotherms, (2) integral, differential, and isosteric heats of adsorption, and (3) heat capacity of the adsorbed phase for surface coverages of the order of a monolayer or less. In line with the preceding, results are presented and discussed for calorimetric studies involving (1) heats of adsorption and heat capacities of methane adsorbed on rutile between 80 and 140°K., (2) heats of adsorption of argon on rutile between 60 and 90°K., and (3) the zero point entropy of krypton adsorbed on rutile at a coverage of about 0.57 of the monolayer capacity.

AN INVESTIGATION OF THE HYDROGEN-CHLORIDE-PROPYLENE REACTION IN THE REGION OF THE CRITICAL TEMPERATURE

1938 ◽  
Vol 16b (12) ◽  
pp. 453-467 ◽  
Author(s):  
C. H. Holder ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Temperature Coefficient ◽  
Hydrogen Chloride ◽  
Liquid State ◽  
Critical Density ◽  
Positive Temperature ◽  
Gaseous State ◽  
Gaseous Mixtures ◽  
Reaction Velocity ◽  
Temperature Range

The reaction between hydrogen chloride and propylene has been studied in the gaseous state above the critical temperature and in the liquid state just below the critical temperature. Pressures were used such that the density of the gaseous mixtures could be made as great as the density of the liquid mixture at some temperature.The rate of reaction above the critical temperature increases slowly with increasing pressure until a certain critical density is attained, after which the rate increases rapidly. In the liquid state the reaction has a positive temperature coefficient except for a 25° temperature range just below the critical temperature. In this region there is a rapid decrease in density of the medium with rise in temperature and a negative temperature coefficient occurs.The density of the liquid reactants at a number of temperatures just below the critical temperature (here defined as the temperature where the visible meniscus disappears) has been reproduced above the critical temperature for a small temperature range. The reaction velocity data obtained under these conditions show a minimum in passing through the critical temperature region.The above results have been interpreted on the basis of a "structure" characteristic of the liquid state which favors higher reaction velocity and which may exist above the critical temperature at sufficiently high densities.

THE DISCONTINUITY IN THE VELOCITY COEFFICIENT OF A CHEMICAL REACTION AT THE CRITICAL TEMPERATURE

1931 ◽  
Vol 5 (1) ◽  
pp. 48-63 ◽  
Author(s):  
H. S. Sutherland ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Chemical Reactions ◽  
Chemical Reaction ◽  
Experimental Work ◽  
Liquid State ◽  
High Pressures ◽  
Gaseous State ◽  
Velocity Coefficient ◽  
New Hypothesis ◽  
Orientation Of Molecules

An account is given of an hypothesis dealing with the mechanism of chemical reactions. This hypothesis was the raison d'être for the experimental work, which consisted in measuring the rate of a chemical reaction in a system over a temperature range including the critical temperature and under conditions such that there was a continuity of concentration, when passing from the liquid to the gaseous state of aggregation.An experimental technique for the investigation of reaction mixtures under high pressures and at relatively high temperatures was developed. This method includes several new features which should find considerable application in investigations of this kind.In the reaction investigated, viz., that between propylene and hydrogen chloride, it was conclusively shown that the velocity of the reaction increases with rise in temperature in the liquid state, and that above the critical temperature the velocity of the reaction becomes practically zero. A new hypothesis was put forward with the object of suggesting further work. It depends on regional orientation of molecules in the liquid state which undergoes a rapid diminution at the critical temperature.

scholarly journals Cloud Particles Differential Evolution Algorithm: A Novel Optimization Method for Global Numerical Optimization

2015 ◽  
Vol 2015 ◽  
pp. 1-36 ◽  
Author(s):  
Wei Li ◽  
Lei Wang ◽  
Quanzhu Yao ◽  
Qiaoyong Jiang ◽  
Lei Yu ◽  
...  
Keyword(s):  
Solid State ◽  
Differential Evolution ◽  
Liquid State ◽  
Differential Evolution Algorithm ◽  
Optimization Method ◽  
Benchmark Problems ◽  
Gaseous State ◽  
Mutation Strategy ◽  
Evolution Algorithm ◽  
Cloud Particles

We propose a new optimization algorithm inspired by the formation and change of the cloud in nature, referred to as Cloud Particles Differential Evolution (CPDE) algorithm. The cloud is assumed to have three states in the proposed algorithm. Gaseous state represents the global exploration. Liquid state represents the intermediate process from the global exploration to the local exploitation. Solid state represents the local exploitation. The best solution found so far acts as a nucleus. In gaseous state, the nucleus leads the population to explore by condensation operation. In liquid state, cloud particles carry out macrolocal exploitation by liquefaction operation. A new mutation strategy called cloud differential mutation is introduced in order to solve a problem that the misleading effect of a nucleus may cause the premature convergence. In solid state, cloud particles carry out microlocal exploitation by solidification operation. The effectiveness of the algorithm is validated upon different benchmark problems. The results have been compared with eight well-known optimization algorithms. The statistical analysis on performance evaluation of the different algorithms on 10 benchmark functions and CEC2013 problems indicates that CPDE attains good performance.

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