Initially Developed Catalysts

Au/TiOj and Au/CeOj can also catalyze WGS. For instance, Sakurai and coworkers found that Au/TiO prepared by deposition-precipitation showed higher WGS activity than Au/TiOj, Au e203, AU/AI3O3, and Au/ZnO prepared by coprecipitation [41]. The activity of the optiinal Au/TiO catalyst was comparable to that of a commercial Cu/ZnO/Al Oj catalyst. In another work, Andreeva and cowoikers demonstrated the application of Au/CeO in WGS and studied the influence of gold loading, contact time, H3O/CO ratio on catalytic activity [42]. 

The support effect in WGS was systematically studied by Zanella and coworkers. The authors found that the activities of catalysts followed the sequence of Au/ Ti03 Au/Ce03 Au/A1 03 Au/Si02 [43]. Apparently, gold catalysts based on 

Fe Oj-based modified gold catalysts were developed for WGS. Zhaig and cowoikers prepared a series of Au/Fe Oj-MO catalysts by coprecipitation [44], MO stands for a metal oxide additive with a low content, whereas Fe Oj is the main componait of support. The authors tested the performance of these catalysts in WGS at 200°C, as a function of reaction time (Fig. 10.3) [44]. The initial CO conversions were close to 100%, except that the addition of Bi Oj or MnO decreased activity significantly. Remarkably, the stability of catalyst was decreased significantly when a small amount of TiO was added into the Au/Fe Oj catalyst system, whereas it was enhanced to some extent when a small amount of CrOj, ZnO, CuO, LaPj, MgO, or ZrO was added. In particular, the addition of ZrO can lead to an active and stable catalyst for WGS. hi another work, the addition of both ZtOj and Nb Oj was demonshated to increase the activity and stabihty further [45]. However, the function of different additives is not explicit. 

FIGURE 10.3 CO conversions on Au/Fe Oj-MO catalysts as a function of time on stream in WGS [44]. The reaction was carried out at 200°C. Reprinted with permission from Ref. [44]. Springer. 

The effect of modification is not only dependent on preparation methods, but also related to the concentration of the dopant [58]. For instance, Veser and coworkers found that the CO conversion increased with the La content in Au/La Ce, O, catalysts, peaking when the La content was 25%, and then decreased when the La content was further increased, namely, the activity followed the sequence of Au/ CeO, Au/La , Ce , 0, Au/La Ce 0, Au/La jCe,, 0, Au/ 

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Although the process is of significance, it has not well studied. Since the initial development of the CTA hydropurification process in 1960s , only a few papers have been published, mainly regarding catalyst deactivation [2]. Recently, Samsung Corporation, in collaboration with Russian scientists, developed a novel carbon material-CCM supported palladium-ruthenium catalyst and its application to this process [3]. However, pathways and kinetics of CTA hydrogenation, which are crucial to industrialization, are not reported hitherto. 

As a true testament to the potential long-term impact of H-bonding activation, a number of ureas, thioureas, and acid catalysts are now finding broad application in a large number of classical and modem carbon-carbon bond-forming processes. On one hand, Johnston s chiral amidinium ion 28 was elegantly applied to the asymmetric aza-Henry reactions (Scheme 11.12d). On the other hand, chiral phosphoric acids (e.g., 29 and 30), initially developed by Akiyama and Terada, have been successfully employed in Mannich reactions, hydrophosphonylation reac-tions, aza-Friedel-Crafts alkylations (Scheme 11.12e), and in the first example... 

Cells of the second type were initially developed by Tinker and Morris at Monsanto [4] and subsequently by Penninger [5]. In these systems, the reaction solution is circulated from the autoclave through an external IR cell of relatively small volume. This arrangement means that the cell can be isolated from the main reaction vessel relatively easily (for example in the event of window failure) thus protecting the spectrometer. Cells of this sort can, in principle, be fitted to plants or pilot plants to monitor liquid streams. However, the circulation of solution from the main reaction vessel through an external cell introduces some potential problems. A pressure drop in the circulation system can lead to release of dissolved gas, which may accumulate between the cell windows and interfere with the spectroscopic measurement. A change in pressure may also influence the catalyst specia-tion, such that the observed spectra may not be truly representative of the bulk reaction solution. 

Recently, rare-earth metal complexes have attracted considerable attention as initiators for the preparation of PLA via ROP of lactides, and promising results were reported in most cases [94—100]. Group 3 members (e.g. scandium, yttrium) and lanthanides such as lutetium, ytterbium, and samarium have been frequently used to develop catalysts for the ROP of lactide. The principal objectives of applying rare-earth complexes as initiators for the preparation of PLAs were to investigate (1) how the spectator ligands would affect the polymerization dynamics (i.e., reaction kinetics, polymer composition, etc.), and (2) the relative catalytic efficiency of lanthanide(II) and (III) towards ROPs. 

The Pd(OAc)2/pyridine catalyst system, initially developed for aerobic alcohol oxidation [41,42], was shown by Stahl and coworkers to be highly... 

Since the mid-fifties sulfonated resins based on styrene/divinylbenzene copolymers, initially developed as ion exchangers mainly for water treatment, nave also been used as strongly acidic solid catalysts. Witn few exceptions, industrial application in continuous processes is limited to the manufacture of bulk chemicals, sucn as Disphenol A, (meth)acrylates, metnyl ethers of branched olefins (MTBE, TAME) and secondary alcohols (IPA, SBA). 

Abstract. This paper reviews ring-opening polymerization of lactones and lactides with different types of initiators and catalysts as well as their use in the synthesis of macromolecules with advanced architecture. The purpose of this paper is to review the latest developments within the coordination-insertion mechanism, and to describe the mechanisms and typical kinetic features. Cationic and anionic ring-opening polymerizations are mentioned only briefly. 

As most of the chiral nucleophilic catalysts that have been described to date were initially developed or tested for Type I acylative KR of sec-alcohols, these are the first class of reactions considered here. 

In the case of pillared clays (PILCs), notwithstanding the fact that these materials were initially developed as catalysts, there have also been other investigations, where PILCs have been studied as potential sorbents, especially for gas separation applications. These materials have a developed micropore structure with a relatively large BET surface area, normally between 300 and 400m2/g and a micropore volume around 0.15 cm3/g [154,155],... 

Equilibrium-restricted reactions (Section A9.3.3.1) have until now been the main field of research on CMRs. Other types of application, such as the controlled addition of reactants (Section A9.3.3.2) or the use of CMRs as active contactors (Section A9.3.3.3), seem however very promising, as they do not require permselective membranes and often operate at moderate temperatures. Especially attractive is the concept of active contactors where the membrane being the catalyst support becomes an active interface between two non-miscible reactants. Indeed this concept, initially developed for gas-liquid reaction [79] has been recently extended to aqueous-organic reactants [82], In both cases the contact between catalyst and limiting reactant which restricts the performance of conventional reactors is favored by the membrane. 

Since NHC are excellent phosphane mimics, the use of functionalised carbenes as ligands in olefin polymerisation catalysts would be self evident. An excellent model reaction is the commercially used Shell Higher Olefin Process (SHOP), initially developed by Keim [100-102], Here, enolisable ketophosphanes are used as ligands for nickel(II) catalysts (see Figure 2.13). A variant of this is the use of phosphino phenol ligands introduced by Heinicke [103-105]. 

Commercially, the catalytic synthesis of ammonia from hydrogen and nitrogen remains of great importance almost ninety years after its initial development. Although Fe is the most widely used catalyst for this process, Ru is known to be more active than Fe.34 Ammonia synthesis using Fe catalysts is relatively well understood. The rate limiting process in the overall Fe-catalyzed reaction is the initial dissociation of N2. The overall reaction can be described as follows ... 

Although lanthanocene catalysts initially developed for aminoalkene hydroami-nation are highly sensitive and not readily available, their catalytic activity remains unsurpassed as of now and only a few postmetallocene rare-earth metal complexes can reach comparable levels of catalytic efficiency. Besides constrained-geometry (Fig. 15) [118, 119] and other half-sandwich [102, 120, 121] rare-earth metal complexes, a large number of cyclopentadienyl-free catalyst systems have been... 

In three parts of work to optimize the coriq)osition of promoters and main con )onents, as well as the reaction conditions, totally, 81 experimental points were tested. The best ACN yields of each part are shown in Figure 8. The best Yacn was raised sharply from initial 34.9% to final 58.9%. This fact demonstrates the proposed technique is very effective for developing catalysts. 

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