Catalyst conditioning

Entry Substrate Catalyst Conditions ee cis/trans Reference... 

Changes in Feed Properties Changes in Catalyst Conditions Changes in Operating Conditions Changes in Mechanical Conditions ... 

In practice once a desirable catalyst condition was achieved x-ray measurements often were taken at temperature and after quenching to 90 K In an attempt to minimize thermal smearing of the EXAFS data. 

The series of deviation from a strictly octahedral crystal field follows the sequence ammonium tungstate > tungstic acid > WO3 [14]. The s->d transition becomes allowed as distortion of the octahedral environment increases. Viewed as a fingerprint technique. Figure 6 shows that the bulk of W present in both WZ (calcined) and PtWZ(acac, reduced) behaves as WO3, as also shown by our XRD data [10], sugesting that only a small extent of W reduction is expected to have taken place during catalyst conditioning prior to reaction. 

Table 2 Specific surface area of fresh and used catalysts, conditions 523 K, 2 MPa, and 540 min.

Catalyst Condition/ Metal Location Dispersion, (%) / metal crystallite Size(nm) Reaction Time (hours) Product Distribution% ... 

Fig. 5.13 H2 consumption in the hydrogenation of 1-hexene over various Pd catalysts. Conditions 1 atm. H2, 23 0.5°C. (X) Pd black, (A) conventional Pd/Al203, ( ) Pd/Al203 sonochemically prepared in 20 mM methanol, (O) Pd/Al203 sonochemically prepared in 20 mMl-propanol [31]...

Scheme 4. Yields of intramolecular competition between E and Z double bonds upon cyclopro-panation with EDA in the presence of different catalysts. Conditions 22 °C molar ratio 800 (diene)/200 (EDA)/1 (catalyst).

Diazo compound Catalyst Conditions Ratio [diazo comp.]/ [catalyst]... 

Kossev, K., Troev, K., and Roundhill, D.M., Synthesis of dialkyl 1,2-epoxy-phosphonates under phase-transfer catalyst conditions, Phosph., Sulf, Silic. Relat. Eletn., 83, 1, 1993. 

Entry Substrate Catalyst Conditions TON TOF [h-1] Conv. [%] ee [%] Refer- ence )... 

Entry Substrate Catalyst Conditions TON TOF Conv. ee Refer-... 

Aided by these developments, the past five years has seen a rapid growth in this area. A breakthrough was the introduction of iridium catalysts with chiral P,N ligands. A large number of new P,N and other ligands have been synthesized and applied to the hydrogenation of unfunctionalized alkenes. This chapter details the catalysts, conditions and substrates used in the enantiomeric hydrogenation of unfunctionalized alkenes. 

Bando and coworkers99 published a study where water-gas shift was used in an applied manner, to assist in the methylation of arylacetonitrile with formaldehyde, using RhCl3 as the homogeneous catalyst. Conditions T = 200 °C Pco = 101 atm 20 mg RhCl3 3H20 20 mmol arylacetonitrile 60-200 mmol paraformaldehyde 5 ml w-methylmorpholine 1 ml H20 and 10 ml dioxane 5 hours of reaction time. Results of their findings are presented in Table 25, and their proposed mechanism is shown in Scheme 38. 

Catalyst Conditions Rate (mol/g cat per second) BET SA (m2/g) Au crystallite size (nm) Ceria crystallite size (nm)... 

This requires 4-12 hr, depending on catalyst conditions. Progress of the reaction can be monitored by TLC. 

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