Strength of adsorption

The relative strengths of adsorption of these compounds foUow the same order, as expected for a nonpolar adsorbent, except that was adsorbed... 

A variety of catalysts including copper, nickel, cobalt, and the platinum metals group have been used successfully in carbonyl reduction. Palladium, an excellent catalyst for hydrogenation of aromatic carbonyls is relatively ineffective for aliphatic carbonyls this latter group has a low strength of adsorption on palladium relative to other metals (72,91). Nonetheless, palladium can be used very well with aliphatic carbonyls with sufficient patience, as illustrated by the difficult-to-reduce vinylogous amide I to 2 (9). 

Equations have been derived for less ideal situations, involving quasi-reversible and irreversible adsorbing electroactive molecules and different strengths of adsorption... 

Opcn-ciitnit actks am strength of adsorption Weak adsorption Raft DuSit.i e order in i > v. cdk adsorption Rate positive order in A 5r/f pA>()... 

Open- circuit ant strength of adsorption. ateposi. ier in D Rate positive order in A fVapA>0... 

This very interesting work is the first demonstration of NEMCA for a hydrogenation reaction in aqueous solutions. It is also the first demonstration of NEMCA in an acidic solution, as all previous electrochemical promotion studies in aqueous media were restricted to alkaline solutions. This work also underlines the importance of the supporting electrolyte and of the strength of adsorption of the anions in aqueous electrochemical promotion studies. 

From adsorption isotherms and competitive adsorption experiments (ref. 19) the strength of adsorption of the reaction components on zeolite CaY appeared to be HBr > o-dibromo > bromo- > p-dibromobenzene > Br2. 

The amoimt and strength of hydrogen adsorption changed with the adsorption temperature for all catalysts examined. As the adsorption temperature was raised, the amount and strength of adsorption increased. 

Tran -isomers have been shown to be much less reactive than the respective cis-isomer. This is due to strong adsorption of the trans-isomsr. The strength of adsorption is such that in many systems the trans-i ovaex acts as a poison. Co-... 

The anchoring effect, which is also sometimes called the haptophilic effect, results from the fact that certain groupings increase the strength of adsorption of... 

As stated above, when probes with specific adsorption characteristics are used, additional chemical information can be extracted from adsorption-desorption experiments. Temperature-programmed desorption (TPD) in particular is often employed to obtain information about specific sites in catalysts [55,56], The temperature at which desorption occurs indicates the strength of adsorption, whereas either the amount of gas consumed in the uptake or the amount of desorption upon heating attests to the concentration of the surface sites. The most common molecules used in TPD are NH3 and C02, which probe acidic and basic sites, respectively, but experiments with pyridine, Oz, H2, CO, H20, and other molecules are often performed as well [57-59], As an example, the ammonia... 

Differential pulse voltammetry and electrochemical impedance have demonstrated that G, A, guanosine, and their oxidation products are electrostatically adsorbed on GC and GC(ox) surfaces [47,49]. The strength of adsorption of the DNA bases on the GC surface were found to be similar [49]. Strongly adsorbed G dimers were formed on GC between G and the adsorbed G oxidation products, which slowly cover and block the surface. The appHcation of ultrasound led to removal of the adsorbed species. The effect of this was mainly to enhance transport of electroactive species and to clean the electrode in situ, avoiding electrode fouling. 

In recent papers (1-2), we have shown how the thermodynamics of adsorption of nonionic surfactants on latex surfaces can be described in terms of a few simple parameters that may be used to predict the relative strength of adsorption of surfactants with different hydro-philic/hydrophobic balance on surfaces of different polarity. 

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