Clays catalyst: clay ratio

Table 1 shows chemical compositions of clay catalysts measured by XRF analysis. Si02 and AI2O3 are main components of the three clay catalysts with minor amount of Na20, Fc203 and others. The Si/Al ratio increased from HH [Pg.434]

The compatibilization of clay with LDPE and HDFE is accomplished by the in situ polymerization of MAH or its precursor maleic acid, in the presence of a radical catalyst. The latter must be capable of initiating the homopolymerization of MAH, i.e. it must be present in high concentration and/or have a half-life of less than 30 min at the reaction temperature, e.g. t-butyl per-benzoate (tBFB) at 150°C. In a one-step process, the clay and PE are mixed with MAH-tBPB in the desired PE/clay ratio. In the preferred two-step process, a 70/30-90/10 clay/PE concentrate is prepared initially in the presence of MAH-tBPB and then blended with additional PE to the desired clay loading. The compatibil-ized or coupled PE-MAH-clay composites have better physical properties, including higher impact strengths, than unfilled PE or PE-clay mixtures prepared in the absence of MAH-tBPB. 

The BET surface areas, pore volumes and pore size distributions for all catalysts investigated are summarized in Table 1. S-lOTi sample showed high specific surface area. But, according to the increase of Ti/clay ratio, the surface area was decreased. This result indicates that the higher Ti/clay ratio leads to a progressive plugging of the internal structure of the clay. 

The first products resulting from this unit were in line with expectations based on the 100 b/d pilot plant operations. The reactor feed had a 31.3 API gravity South Louisiana reduced crude including a slurry oil recycle (17 API) rate of 4% on feed. The reactor temperature was 910° F. with the cat to oil ratio of 3.5. A 53.5 vol% conversion was obtained with Super Filtrol natural clay catalyst. The regenerator operated at 1052° F., the spent catalyst containing 1.6 wt% carbon while the regenerated catalyst was reduced to 0.5 wt%. Flue gas excess oxygen was 4.4 wt%. The observed yields for PCLA 1 are recorded in Table II. 

The A1 content fixed by the pillared clay increases with the pH and with the Al/clay ratio. According to the preparation process, the whole amount of the pillaring Al-species is not always completely fixed in the interlayer space. For some samples, it may be suspected that another Al-species is precipitated to a greater or lesser extent on the layer surface. The best stability of Al-pillared saponite is obtained under the following experimental conditions clay concentration < 5 g.l Al/clay < 5 mmol.g and pH values between 4.8 and 6.0. A very carefull thermal treatment is required up to SOOX (36 /h heating rate) to transform the intercalated species into oxide pillars. At 750 C, the surface areas are about 150- 250 m. g and the basal spacings dpoi about 17.3 A. According to these values, Al-pillared saponites may be used as catalysts of 7-8 A pore space. 

Bakke et al. (1982) have shown how montmorillonite catalyses chlorination and nitration of toluene nitration leads to 56 % para and 41 % ortho derivative compared to approximately 40 % para and 60 % ortho derivatives in the absence of the catalyst. Montmorillonite clays have an acidity comparable to nitric acid / sulphuric acid mixtures and the use of iron-exchanged material (Clayfen) gives a remarkable improvement in the para, ortho ratio in the nitration of phenols. The nitration of estrones, which is relevant in making various estrogenic drugs, can be improved in a remarkable way by using molecular engineered layer structures (MELS), while a reduction in the cost by a factor of six has been indicated. With a Clayfen type catalyst, it seems possible to manipulate the para, ortho ratio drastically for a variety of substrates and this should be useful in the manufacture of fine chemicals. In principle, such catalysts may approach biomimetic chemistry our ability to predict selectivity is very limited. 

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