Catalyst changeover

OTHER Maintenance 1. Equipment failure, flange leak, catalyst changeover in reactor, etc. Process stops. Ensure all pipes and fittings are constructed of the right materials and arc stress relieved. 

Catalyst Changeover. Metals Content. The equilibrium sample of a USY octane catalyst, Catalyst A, was withdrawn from an Amoco FCU. Results of metals analyses on the equilibrium catalyst and on its parent are given in Table I. Catalyst A was introduced to the unit during a five-month period over Catalyst B, which was identical to Catalyst A in all respects, except for a low level of contaminant rare earth. Catalyst B had, in turn, been introduced over a rare earth-containing catalyst, Catalyst C, eight months prior to withdrawal of the equilibrium sample. Catalyst history and rare earth contents are summarized in Table II. 

When a refiner changes the FCC catalyst, it is often necessary to determine the percent of the new catalyst in the unit. The following equation, which is based on a probability function, can be used to estimate the percent changeover. 

The 300-ton inventory unit in Example 3-2 is changing catalyst type and planning to add 3.5 tons per day of new catalyst. Determine the percent of changeover after 60 days of operation. Assume a retention factor of 0.7. 

For the same 300-ton inventory unit, assume the alumina (AljOj) contents of the present and new fresh catalysts are 48 wt% and 38 wt%, respectively. Sixty (60) days after the catalyst switch, the alumina content of E-cat is 43 wt%. Determine % changeover ... 

Dramatic changeover is observed not only in the ene/HDA product ratio, but also in the absolute stereochemistry upon changing the central metal from Ti to Al. Thus, Jprgensen et al. reported the HDA-selective reaction of ethyl glyoxylate with 2,3-dimethyl-1,3-butadiene catalyzed by a BINOL-derived Al complex [25], where the HAD product was obtained with up to 89% periselectivity and high enantiopurity (Scheme 8C.9). The absolute configuration was opposite to that observed by using BINOL-Ti catalyst. 

Estimated changeover based on rare earth material balance - 88% Fresh Catalyst Addition Rate (see text) 2% of inventory/day... 

During the five months of operation with the zero rare earth octane catalyst, the effective fresh catalyst addition rate, after correction for catalyst loss from the unit as fines, was about 5 tons/day. Based on a rare earth material balance (Table II) that was used to give the best estimate of pedigree, the equilibrium sample consists of 88% USY octane catalyst. The remaining 12% should be a mixture of the prior two catalysts, the first of which contains a contaminant rare earth level of 0.5 wt% versus 0.1 wt% for the octane catalyst. The balance of this mixture is the rare earth-Y catalyst from the previous changeover which exhibits a rare earth level of 0.85 wt% (Table II). 

A "remnant" rare earth catalyst found in the high-density tail of the distribution is associated with incomplete changeover (88%) of this USY catalyst. This result indicates that density separation may not yield a good age profile in those cases where a rare earth catalyst has been introduced over a zero rare earth USY catalyst. Significant inhomogeneity within the parent (fresh) catalyst will also compromise the age/density correlation. 

This process produces a wide melt index range by applying innovative catalyst chemistry combined with a sophisticated polymerization process. An all-round catalyst and simple polymerization operation provide easy product changeover that reduces transition time and yields negligible off-spec product from the transition. Mitsui has also developed new catalyst that contributes better morphology of the polymer powder and ethylene consumption. 

Changeover from homogeneous to heterogeneous catalysis, particularly when this is required because of environmental problems or technical problems, such as separation of the catalyst. 

A changeover from part B to part A of Fig. 4 is an important goal of GDE optimization in order to increase performance and/or to decrease catalyst demand. Highly sophisticated techniques for high dispersion, which simultaneously guarantee the connection between catalyst particles, have to be developed. 

At 20 °C, irradiation causes an increase in molecular weight whilst at 200 °C a decrease occurs. The changeover occurs at about 100 °C. Pre-irradiation causes destabilization of polypropylene, and the sensitivity of polypropylene to radiation at 253.7 nm is believed to be due to titanium residues from the polymerization catalysts [822] (section 2.21). 

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