Adsorption of Benzene in Carbon Slurries

Misic, Dragoslav M.; Smith, J. M.

doi:10.1021/i160039a007

Cited by 25 publications

(16 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The requirement for this linearity is that the bubble size does not change with gas flow rate. The bubble diameter as measured by Misic and Smith (1971), over a range of Q values similar to those used in our experiment with a similar dispersion tube, did not change significantly.…”

Section: Methods Of Analysissupporting

confidence: 57%

Slurry reactor studies of homogeneous and heterogeneous reactions

McCoy

Smith

1989

AIChE Journal

Self Cite

View full text Add to dashboard Cite

A dynamic model is derived for simultaneous, homogeneous and heterogeneous, first-order reactions in a slurry reactor. The theory is applied to experimental data for the oxidation (with gaseous oxygen) of aqueous sulfite solutions which is first order in oxygen and zero order in sulfite. The homogeneous reaction is very slow at low pH (2-3) where the sulfur exists as dissolved SO, or HS03-, even when cobalt is added as a homogeneous catalyst. At higher pH (7-8.5), considerable homogeneous reaction occurs with and without cobalt ions. Here the predominant species are SO3' and HS03-. Activated carbon is not a heterogeneous catalyst at pH 7 or 8.5, but is responsible for nearly all the reaction at the low pH values. Analysis of the heterogeneous data indicates that the surface reaction between adsorbed oxygen and SO2 controls the rate rather than adsorption of oxygen.

show abstract

Section: Methods Of Analysissupporting

confidence: 57%

Slurry reactor studies of homogeneous and heterogeneous reactions

McCoy

Smith

1989

AIChE Journal

Self Cite

View full text Add to dashboard Cite

show abstract

“…Hence, complete mixing was assumed for this phase. Even for an agitated slurry the bubble stream is not well mixed (Juvekar and Shanna, 1973;Misic and Smith, 1971). The latter authors showed that plug flow of gas well represented their data for benzene adsorption in an agitated, aqueous slurry of activated carbon.…”

Section: Adsorption Of Sulfur Dioxidementioning

confidence: 93%

Sulfur dioxide oxidation in slurries of activated carbon. Part I. Kinetics

Komiyama

Smith

1975

AIChE Journal

Self Cite

View full text Add to dashboard Cite

Part 1. KineticsDynamic adsorption and reaction studies were made for the catalytic oxidation of sulfur dioxide in aqueous slurries of activated carbon at room temperature and atmospheric pressure. For the small particles (d, = 0.03 mm) of carbon used, mass transfer resistances were of minor importance SO that the data could be analyzed in terms of the kinetics of the chemical reaction. Quantitative evaluation of mass transfer effects, including intraparticle diffusion, is presented in Part 11.The rate was first order in oxygen concentration in the liquid and zero order with respect to SOz. The rate decreased with increasing HzS04 concentration in the liquid. This was explained by the decrease in solubility of oxygen in the solution rather than by a change in reaction rate constant. The adsorption and rate data together suggest that the controlling step in the mechanism is the adsorption of oxygen on active sites of the carbon surface. The low concentration of oxygen in water (due to its low solubility) reduces its rate of adsorption. SCOPEActivated carbon is known to catalyze oxidation of SOz at room temperature. This provides a potential process for continuous removal of sulfur dioxide from gas streams. The comprehensive review of Hartman et al. (1971) notes that chemisorbed oxygen has a role in the oxidation process and that the presence of water removes the adsorbed SO3 molecules, thus renewing the active sites. Also these authors found that H2S04 slows the rate of oxidation. Unless water is continuously added the buildup of HzS04 in the solution (containing the activated carbon) will ultimately cause the reaction to stop.The kinetics of the reaction, with water present, are not well understood, particularly the role of oxygen and HzSO4. Hartman and Coughlin (1972) interpreted tricklebed reactor data in terms of kinetics which supposed that the surface rate between adsorbed atomic oxygen and adsorbed sulfur dioxide to be rate determining. Since the inlet concentration to the reactor was constant, the results were not a stringent test of the kinetics model. Also intraparticle diffusion was not separated from the intrinsic rate constant. These authors also pointed out the effect of H2S04 in decreasing the solubility of sulfur dioxide in aqueous solutions. Other studies of this system have not analyzed the kinetics of the oxidation reaction. Joyce et a].(1970) reported trickle-bed studies of the recovery of SOz from gas streams. Sulfuric acid of 12y0 concentration was obtained with an excess of oxygen and at 100OC. Seaburn and Engel (1973) compared several activated carbons of different particle sizes in terms of capacity for adsorbing SO, and catalytic activity for the oxidation reaction. Intraparticle diffusion resistances for the various carbons were not considered.The present work was undertaken to clarify the adsorption and reaction characteristics of the oxygen-sulfur dioxide-activated carbon-water system in a three-phase slurry reactor. Part I presents an analysis of data showing predominantly the chemica...

show abstract

“…Then, the liquid phase concentration at the gasliquid interface is that in equilibrium with the bulk gas value. Since Henry's law is valid for benzene in water at low concentrations and 298"K, the interface Concentration is C = CJH, where H = 0.20 (Misic and Smith, 1971). Also, the physical adsorption of benzene on activated carbon is intrinsically rapid.…”

Section: Theorymentioning

confidence: 99%

“…In using the zero moment data, a is first calculated from Equation (12), after /3 is evaluated from the liquid and gas flow rates and the Henry law constant. As mentioned, H was taken as 0.20 at 25°C (Misic and Smith, 1971). However, the value of a is not very sensitive to H ; a 60% change in the Henry law constant causes an 8% change in (ka),.…”

Section: Gas-to-liquid Mass Transfer Coefficient (Trickle Bed Data)mentioning

confidence: 99%

Surface tensions of binary liquid systems. I. Mixtures of nonelectrolytes

Lam¹,

Benson²

1970

Can. J. Chem.

View full text Add to dashboard Cite

Mass Transfer and Adsorption in Liquid Full and Trickle BedsExperimental breakthrough curves were determined for a liquid full and a trickle bed reactor in which benzene was adsorbed from water on small activated carbon particles at 298°K and 1 atm. The step function of benzene was introduced into the water feed and the response measured in the liquid effluent. Benzene transfer a1r;o occurred from the liquid feed to the gaseous feed of pure helium.Moment analysis of data for liquid full conditions indicated that the first moment of the response curve could be used to obtain the adsorption equilibrium constant K for benzene on activated carbon. Comparison of results obtained by this new method with the K value determined from static equilibrium runs demonstrated the validity of the moment theory.Analysis of the response curves for trickle bed operation showed that the liquid-to-gas mass transfer coefficient (ka), could be evaluated from either the zero or first moment. Results were obtained in both the trickling flow and pulse flow regimes. Values of (ka), in the pulse flow regime, which were not heretofore available, were sharply higher than those for trickle flow. SCOPEMass transfer between gas and liquid and also between liquid and catalyst particles can significantly affect the performance of trickle bed reactors (Satterfield, 1978;Goto and Smith, 1975). Steady state methods have been used to obtain transport coefficients in the trickling flow (gas continuous) and pulsing flow regimes by steady state studies. These experiments have been carried out by two methods: in the absence of reaction by dissolution of solids which were unlike porous catalyst particles, or under catalytic reaction conditions where reaction effects have to be accounted for before mass transfer effects are evaluated.One objective of our research was to use breakthrough curve (BTC) data to evaluate the gas-liquid mass transfer coefficient (ka),. Also, we wanted to carry out the experiments under conditions of rapid physical adsorption. Then equilibrium could be assumed at an intraparticle adsorption site, avoiding the complications of finite reaction rate and possible variations in catalyst activity, etc. The procedure was to measure breakthrough curves in the liquid effluent when a step function of

show abstract

Adsorption of Benzene in Carbon Slurries

Cited by 25 publications

References 10 publications

Slurry reactor studies of homogeneous and heterogeneous reactions

Slurry reactor studies of homogeneous and heterogeneous reactions

Sulfur dioxide oxidation in slurries of activated carbon. Part I. Kinetics

Surface tensions of binary liquid systems. I. Mixtures of nonelectrolytes

Contact Info

Product

Resources

About