Effect of Support

Another recent trend focused on supports in the shape of monolithic columns having the goal to benefit from the high permeability and the improved mass transfer characteristics of such structures. With this goal in mind, Lubda and Lindner [75] prepared enantioselective silica monolith columns with tert-butylcarbamoylquinine surface modification. A commercial sol-gel-derived Chromolith Performance Si (100 X 4.6 mm ID) monolith (1.9 tim macropore diameter, 12.5 nm mesopore 

A side aspect was also demonstrated. If required, the column length and thus the peak capacity can be easily amplified by coupling several enantioselective monolithic columns in series [75]. The actual plate count for a single 10-cm-long monolith was about 7,000 for suprofen and it amounted to about 30,000 for six columns in series. Concomitantly, the resolution was improved from 2.1 to 3.5 while the backpressure of the 60-cm-long column was with 45 bar still quite acceptable (opposed to six bar for a single 10-cm-long column). 

Zirconia particles have been promoted recently as support replacing silica with the proposed advantage of better chemical, thermal, and mechanical stability. Such zirconia-supported chiral phases have been prepared by Park and coworkers [77] through coating, for example, of 0-9-[3-(triethoxysilyl)propylcarbamoyl]quinine onto 5 p.m zirconia particles (30-nm pore diameter) or carbon-cladded zirconia particles as support [78]. In comparative tests with corresponding silica materials. 

Moreover, in-situ copolymerization approaches of polymerizable chiral cin-chonan carbamate selectors have also been shown to be viable straightforward routes to enantioselective separation media. In one approach, polymethacrylate-type monoliths have been fabricated by copolymerization of functional monomers and crosslinker in presence of porogenic solvents [80-85]. They have been utilized mainly for CEC (and will be described in detail later) while they turned out to be less suitable for HPLC application because of a low crosslinking degree. 

---

The effect of support materials on the enantiomeric excess(ee)% of product. 

The Effect of Support-Metal Precursor Interactions on the Surface Composition of Supported Bimetallic Clusters... 

Table 2. Effect of support particle on the size of precursor and metal particles of Pt.

Effect of Support on Conversion and Selectivity on Ni/Re Catalyst Compositions... 

Figure 34.6a and b. Effect of support on conversion and selectivity for Ni/Re catalyst composition. 

Viswanathan, B., and Gopalkrishnan, R. 1986. Effect of support and promoter in Fischer-Tropsch cobalt catalysts. J. Catal. 99 342-48. 

Reuel, R.C., and Bartholomew, C.H. 1984. Effects of support and dispersion on the carbon monoxide hydrogenation activity/selectivity properties of cobalt. J. Catal. 85 78-88. 

A-5.2.3 Effects of Support, Anchor, and Terminal Movements. The use of pads or other means of pipe attachment at support points should be considered for piping systems subject to wear and pipe wall metal loss from relative movement between the pipe and its supports. 

As indicated above, all of the experimental data reported thus far were obtained at low concentrations of both supporting electrolyte (mM) and electroactive species (pM). This was done because we have observed an interesting effect of supporting electrolyte concentration on the shape of the voltammetric waves observed at the NEEs [25]. We have found that the reversibility of the voltammetric waves for all couples investigated to... 

EIG. 10. Cyclic voltammograms illustrating the effect of supporting electrolyte concentration at a lONEE. 5 pM TMAFc in aqueous NaNOs at the indicated concentrations of NaNOs. Scan rate = 100 mV s h... 

Effects of Support, Anchor, and Terminal Movements The effects of movements of piping supports, anchors, and connected equipment shall be taken into account in the design of piping. These movements may result from the flexibility and/or thermal expansion of equipment, supports, or anchors and from settlement, tidal movements, or wind sway. 

Effect of Support Materials. The carbonylated products were methyl acetate (AcOMe) and acetic acid (AcOH) as Equations 1 and 2. 

Experimental data on heat transfer from spheres to an air stream are shown in Fig. 5.20. Despite the large number of studies over the years, the amount of reliable data is limited. The data plotted correspond to a turbulence intensity less than 3%, negligible effect of natural convection (i.e., Gr/Re <0.1 see Chapter 10), rear support or freefloating, wind tunnel area blockage less than 10%, and either a guard heater on the support or a correction for conduction down the support. Only recently has the effect of support position and guard heating been appreciated a side support causes about a 10% increase in Nu... 

Haruta et al. recognized the high effectiveness of supported gold nanocrystals for the oxidation of CO at very low temperatures, unlike the low activity displayed by other metals [11, 257]. 

The situation considered in Sects. 4.4—4.6 is one of the few cases in which the effect of supporting electrolyte can be examined quantitatively. Nevertheless, it is reasonable to assume that the same principles held in situations, transient as well as steady state, that cannot be treated exactly. Certainly the attitude of electrochemists to migration is add supporting electrolyte and forget it . This will be our attitude in most of the rest of the chapter. 

Copper-catalysts promoted with i) other group VIA or VIIIA metals and ii) alcaline or alcaline earth elements (IA or IIA) are used for selective hydrogenation of various organic compounds (1). Moreover Cu(Co) Zn-Al catalysts were extensively studied for the synthesis of methanol and of light alcohols (2,3). More recently, due to the development of fine chemical processes, detailed studies of copper catalysts were carried out in order to show, like for noble metals, the effect of supports (SMSI), of promoters and of activation-on metal dispersion or reduction, on alloy formation... For example modified copper catalysts are known for their utilization in the dehydrogenation of esters (4-6), in the hydrolysis of nitriles (7), in the selective hydrogenation of nitriles (8), in the amination of alcohols (9)... 

In a recent more thorough study the effect of supporting electrolyte was examined in detail.26 Salts containing NH or Cl- ions were found to be inferior, while the use of (ButN)Br and (Bu4N)BF4 allowed the processes to be run indefinitely. Using these conductive admixtures the isopropoxides of Y, Sc, Ga and Zr and the ethoxides of Ti, Ge, Nb and Ta were obtained in current yields between 60-97%. Typically potentials of 30-100 V are used, giving currents of 0.05-0.25 A.26 Although studies of this process have been limited so far, it does appear to be the most useful for the direct conversion of the less electropositive metals to their alkoxides. 

---