Cu-based catalyst

The catalyst is a commercial low-temperature Cu-based shift catalyst that makes methanol at high pressure. Of this, V = 20 cm, equal W = 26.5 g is charged in form of 3/16 (4.76 mm) regular cylinders. 

Fig. 2 shows the temperature as a function of irradiation time of Cu based material under microwave irradiation. CuO reached 792 K, whereas La2Cu04, CuTa20e and Cu-MOR gave only 325, 299 and 312 K, respectively. The performances of the perovskite type oxides were not very significant compared to the expectation from the paper reported by Will et al. [5]. This is probably because we used a single mode microwave oven whereas Will et al. employed multi-mode one. The multi-mode microwave oven is sometimes not very sensitive to sample s physical properties, such as electronic conductivity, crystal sizes. From the results by electric fixmace heating in Fig. 1, at least 400 K is necessary for NH3 removal. So, CuO was employed in the further experiments although other materials still reserve the possibility as active catalysts when we employ a multi-mode microwave oven. 

In the above three processes, the catalysts are all composed of Cu-based methanol synthesis catalyst and methanol dehydration catalyst of AI2O3. The reactors used by JFE and APCI are slurry bubble column, while a circulating slurry bed reactor was used in the pilot plant in Chongqing. It can be foxmd from Table 1 that conversion of CO obtained in the circulating slurry bed reactor developed by Tsinghua University is obvious higher and the operation conditions are milder than the others. 

Fig. 4.15), are active for ATRP of both styrene and methylmethacrylate (MMA) [46]. Polymerisation was well controlled with polydispersities ranging from 1.05 to 1.47. The rates of polymerisation 1 x 10 s ) showed the complexes to be more active than phosphine and amine ligated Fe complexes, and were said to rival Cu-based ATRP systems. It was quite recent that Cu(I) complexes of NHCs were tested as ATRP catalysts [47]. In this work, tetrahydropyrimidine-based carbenes were employed to yield mono-carbene and di-carbene complexes 42 and 43 (Fig. 4.15), which were tested for MMA polymerisation. The mono-carbene complex 42 gave relatively high polydispersities (1.4-1.8) and a low initiation efficiency (0.5), both indicative of poor catalyst control. The di-carbene complex 43 led to nncontrolled radical polymerisation, which was ascribed to the insolubility of the complex. 

Scheme 1.1. Proposed mechanism for the NO-NH3 reaction over Cu-based catalysts in the presence of oxygen [31b].

The situation for the hydrosilylation of C = N functions with regard to ecology and economy is somewhat similar as for the hydride reduction, except that fewer effective catalytic systems have been developed [91]. Despite some recent progress with highly selective Ti-based [92] and Cu-based [93] catalysts using cheap polymethylhydrosiloxane as reducing agent, hydrosilylation will see its major applications in small-scale laboratory synthesis. 

Catalyst systems for the WGS reaction that have recently received significant attention are the cerium oxides, mostly loaded with noble metals, especially platinum 42—46]. Jacobs et al. [44] even claim that it is probable that promoted ceria catalysts with the right development should realize higher CO conversions than the commercial Cu0-Zn0-Al203 catalysts. Ceria doped with transition metals such as Ni, Cu, Fe, and Co are also very interesting catalysts 37,43—471, especially the copper-ceria catalysts that have been found to perform excellently in the WGS reaction, as reported by Li et al. [37], They have found that the copper-ceria catalysts are more stable than other Cu-based LT WGS catalysts and at least as active as the precious metal-ceria catalysts. 

As discussed in previous sections, Cu acts primarily as an electronic conductor within the Cu-based anodes. Because it is a poor catalyst for C—H and C—C bond scission, it is essential to incorporate an oxidation catalyst, ceria, within the anode. While Ni has many attractive properties, its propensity for catalyzing carbon formation prevents its use in dry hydrocarbons at high temperatures. One approach for enhancing the catalytic properties of Cu and stabilizing the tendency of Ni for forming carbon is to use Cu—Ni alloys. Cu—Ni alloys have been used... 

Another a, i-unsaturated aldehyde analyzed is cinnamaldehyde. Its liquid-phase hydrogenation has been studied in our research group [20, 51, 94], using Pt, Ni and Cu-based tin-modified hi- and organobimetaUic catalysts (in all cases with Si02 as support). The catalytic results obtained showed that in aU cases there was a marked promoting effect of Sn on the selectivity to cinnamic alcohol (UOL). The specific modification of the monometallic systems due to Sn addition from the application of SOMC/M markedly increases the selectivity to UOL, especially in the case of Ni, where it goes from zero selectivity for the monometallic to 25% for the NiSn catalyst. Pt-based systems modified by Sn yield the best Suol values. 

Two types of catalysts have been proposed for the CPOM reaction copper and palladium. The catalytic properties of these materials show significant discrepancies with respect to by-product formation and the effect of oxygen partial pressure. The Cu-based catalysts display high selectivity for the CPOM reaction whereas for the Pd-based catalysts CO formation is significant. 

Morphological characteristics of the Cu-based catalyst surface play a central role in the evolution of the oxidation state and structural morphology during the reaction, because the dynamic behavior of the catalyst surface is determined by the conditions of the gaseous atmosphere during the reaction. 

In bimetallic catalysts, Cu-Ru is an important system. Combinations of the Group Ib metal (Cu) and Group VIII metal (Ru)-based catalysts are, for example, used for the dehydrogenation of cyclohexane to aromatic compounds and in ethane hydrogenolysis involving the rupture of C-C bonds and the formation of C-H bonds (Sinfelt 1985). Here we elucidate the structural characteristics of supported model Cu-Ru systems by EM methods, including in situ ETEM. 

A new synthesis of cr-substituted and a,a-disubstituted a-amino acid derivatives based on the ammonium ylide formation/[2,3]-sigmatropic rearrangement has been recently reported by Clark s group.Decomposition of a-diazo -keto ester 153 was studied in detail with Rh2(OAc)4, Cu(acac)2, and Cu(hfacac)2 as the catalyst. Cu(acac)2 and Cu(hfacac)2 gave similar results, but Rh2(OAc)4 turned out less effective (Equation (23)). 

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