Cerium on alumina

These materials were made to contain 10 wt% oxides on gamma alumina. The percentage of SO2 removed after 50 minutes was measured, at 1250°F, for these additives at the 1 wt% level mixed with cracking catalysts. They were then ranked by the ratio of the % removed to that removed by cerium on alumina. 

Silica is known to be volatile in steam (39-40). For instance, the equilibrium concentration of silica in steam at 1 atmosphere from 1200 to 1450 F has been found to range from 0.2 to 0.5 ppm (by weight) showing that the availability of silica in the vapor phase can be substantial under the conditions used in our work. Unfortunately, we cannot predict how much silica will be transferred in our experiments since the rates of either hydrolysis or adsorption on the cerium on alumina additive are unknown. 

Figure 17 shows a comparison of the fresh SO2 removal ability for these five major types of commercially available SOx catalysts. The materials were tested at 1350 F at various concentrations with a very low capacity cracking catalyst. The magnesia-based catalyst is much better than lanthanum-based catalyst followed by platinum or cerium on alumina and finally alumina alone. The reverse order in activity observed for the lanthanum-based and cerium additives, compared to the relative results given previously for lanthanum and cerium, was not investigated, but may be related to the presence of cerium on the lanthanum-based additive (27). 

Catalysts used for preparing amines from alcohols iaclude cobalt promoted with tirconium, lanthanum, cerium, or uranium (52) the metals and oxides of nickel, cobalt, and/or copper (53,54,56,60,61) metal oxides of antimony, tin, and manganese on alumina support (55) copper, nickel, and a metal belonging to the platinum group 8—10 (57) copper formate (58) nickel promoted with chromium and/or iron on alumina support (53,59) and cobalt, copper, and either iron, 2iac, or zirconium (62). 

Park PW, Ledford JS (1998) The influence of surface structure on the catalytic activity of cerium promoted copper oxide catalysts on alumina oxidation of carbon monoxide and methane. Catal Lett 50(1—2) 41 48... 

The secret that makes this process work is no surprise, the catalyst. Those that work include some of the noble metals, specifically, platinum or palladium, a rare earth metal like cerium or neodynium (are they rare or what ) on alumina, or a non-noble metal like chromium on a silica-aluminum support. 

This paper identifies alumina, rare earths, platinum, and magnesia as important SOx capture materials. Alumina is either incorporated directly into the matrix of a cracking catalyst or added as a separate particle. Cerium is shown to promote the capture of SO2 on high alumina cracking catalyst, alumina, and magnesia. Other rare earths are ranked by their effectiveness. The promotional effect of platinum is shown between 1200 and 1400 F for SO2 capture on alumina. Silica, from free silica or silica-alumina in the matrix of cracking catalyst, acts as a poison by migrating to the additive. 

Independence from cracking catalyst composition has been shown by adding cerium and alumina to cracking catalyst (25). The data on Table I demonstrate this. 

Catalysts for the chemical industry have to be characterized with respect to their trace impurities and major components. Not only is their composition when they are used initially in chemical reactors important, but also their alteration in the course of time. As carbide forming elements such as V and Ti are often used, atomic absorption spectrometry could be problematic. This also applies to catalysts for exhaust gas detoxification in cars. Noble metals such as Pt, Pd and Rh are fixed on alumina supports often also containing cerium compounds. Both for the determination of the stoichiometry but also for the monitoring of the noble metal contents in used catalysts, AAS suffers from problems because of the need for sample dissolution as well as for the requirement to determine refractory oxide forming elements. 

AgAlBO [28], VMoCrPdOv [29], SbVTi with additives [30], and perovskite systems such as YBaCu30g [31], Cerium oxide (on titania) [32] or nickel oxide (on alumina) have also been used as catalysts in special circumstances. Nowadays, zeolite-supported catalysts, e. g. Cu-exchanged materials such as Cu-H-ZSM-5... 

THERMOSTABILITY OF COPPER-CHROMIUM OXIDE CATALYSTS ON ALUMINA SUPPORT PROMOTED BY LANTHANUM AND CERIUM. 

X-ray method was recently used to study thermal stability of alumina supports promoted with La203 and Ce02 [6,7], as well as phase composition and thermal stability of Cr/Al203, CU/AI2O8 and Cr-Cu/Al208 [8-10]. Here we compare thermal stabilities of Cr-, Cu- and Cr-Cu systems on alumina support promoted by lanthanum and cerium. 

EPR was used to investigate the morphology of Ce02 and mixed cerium oxides (Ce02-Zr02) supported on alumina surfaces. Aggregated crystalline... 

The use of cerium on Ru-based catalysts supported on alumina and activated carbon increased selectivity to unsaturated alcohols in the hydrogenation of crotonaldehyde (in the gas phase) and citral (in the liquid phase with isopropanol as solvent). However, the observed activities were very low. 

It was observed during the 1970s that high-alumina catalysts partly fulfilled these requirements. However, sulfur oxides in the flue gas were only decreased by about 20% because aluminum sulfate decomposes at a relatively low temperature of 580 C. Better absorbeuts were then investigated. Cerium oxide supported on alumina improved the absorption of sulfur trioxide, but performance... 

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