Propylene yield comparison

Another commercial trail of MIP-CGP for processing intermediate-based sour residual feed has been put on stream in SINOPEC Cangzhon Company in 2005. Table 5.6 shows the commercial comparison of CGP-2 and CGP-1. After shifting to CGP-2 the propylene yield increased by 1.15%, and the light ends yield increased by 0.57%. The snlfnr content of gasoline was decreased from 840 to 580 J,g/g. The olehn content, RON and MON of gasoline remained essentially constant. 

A typical FCC operation can yield around 4-5 wt% propylene. The inclusion of ZSM-5 additives (Zeolite structural matrix-5) coupled with high reactor operating temperature (ROT) yields 5-10 wt% propylene with additive concentrations up to 10 wt% as per the industry standard as shown in the table below. This is based on data from commercially operating units around the world. A comparison of propylene yield from various catalytic cracking options is summarized below ... 

Figure i. Comparison of Davison fluid catalysts for cracking west Texas gas oil Lower propylene yields and higher gasoline yields result with molecular sieve XZ-15 vs. high activity silica alumina (5). 

The data analysis with the help of Eqs. (83), (84), (87), and (88) where association constants are used with MSA activity coefficients [Eqs. (90), (91), (92)] yields a good reproduction of experimental data up to molar concentrations. As an example. Fig. 9 shows the conductivity of BU4NCIO4 in the mixed solvent system acetonitrile-propylene carbonate. Comparison is made of measured data with MSA and the Amis-Casteel equation, which both exactly reproduce the conductivity maximum at every solvent composition. 

Table II summarizes the yields obtained from the CONGAS computer output variable study of the gas phase polymerization of propylene. The reactor is assumed to be a perfect backmix type. The base case for this comparison corresponds to the most active BASF TiC 3 operated at almost the same conditions used by Wisseroth, 80 C and 400 psig. Agitation speed is assumed to have no effect on yield provided there is sufficient mixing. The variable study is divided into two parts for discussion catalyst parameters and reactor conditions. The catalyst is characterized by kg , X, and d7. Percent solubles is not considered because there is presently so little kinetic data to describe this. The reactor conditions chosen for study are those that have some significant effect on the kinetics temperature, pressure, and gas composition.

Also included in Table IV are the metastable product yields for comparison to the ion beam and IR activation results. From these data it appears that the processes involving elimination of hydrogen and methane involve a competitive dissociation from a common intermediate as shown in Figure 16. However, a common intermediate may not be involved in the elimination of ethylene and propylene (the latter product appears to be formed in a faster process), and Scheme HI is overly simplistic. 

Metathesis activity. A quantitative comparison of metathesis activities was made in the gas phase homometathesis of propylene. The reaction kinetics are readily monitored since all olefins (propylene, ethylene, cis- and fra/3s-2-butylenes) are present in a single phase. Metathesis of 30 Torr propylene was monitored in a batch reactor thermostatted at 0 °C, in the presence of 10 mg catalyst. The disappearance of propylene over perrhenate/silica-alumina (0.83 wt% Re) activated with SnMe4 is shown in Figure 2a. The propylene-time profile is pseudo-first-order, with kob (1.11 + 0.04) X 10" slightly lower rate constant, (0.67 constants are linearly dependent on Re loading. Figure 3. The slope yields the second-order rate constant k = (13.2 + 0.2) s (g Re) at 0°C. 

In addition some p.opane and n-hexane are formed. These are also believed to originate from the trimethylene diradical. A direct comparison of these results with the results reported by other workers is not possible since the only other study in the presence of a foreign gas involved water vapor at a pressure of 70 mm. (5). In the latter instance the ketone pressure was 136 mm., which is 5 to 10 times greater than the pressure used in ref. (17). The presence of water vapor does not seem to have affected the yields of propylene and of cyclopropane. Since the diradical mecha-... 

In comparison to the bismuth molybdate and cuprous oxide catalyst systems, data on other catalyst systems are much more sparse. However, by the use of similar labeling techniques, the allylic species has been identified as an intermediate in the selective oxidation of propylene over uranium antimonate catalysts (20), tin oxide-antimony oxide catalysts (21), and supported rhodium, ruthenium (22), and gold (23) catalysts. A direct observation of the allylic species has been made on zinc oxide by means of infrared spectroscopy (24-26). In this system, however, only adsorbed acrolein is detected because the temperature cannot be raised sufficiently to cause desorption of acrolein without initiating reactions which yield primarily oxides of carbon and water. 

Pistoia investigated the electroinitiated polymerisation of styrene in propylene carbonate-lithium perchlorate solutions at 25°C. Mechanistic evidence was obtained for the formation of perchloric acid at the anode and the cationic nature of the process thus proved. The kinetic analysis yielded a kp value of 0.5 M sec . Although no comparisons can be made between this result and previous ones in other solvents, the presence of lithium perchlorate was here a source of homocorgugation for the acid produced and thus the cause of considerable deactivation of its initiating power. As in previous cases, this was not recognised by the author. A simflar study by Pistoia and Scro-sati in dimethylsulphate gave an insoluble polymer at the anode and the nature or the initiator was not elucidated, but it did not seem to be perchloric acid. The cationic properties of this process was however proved... 

A comparison [32] of standard (ASTM and DIN) Charpy notch-impact test results with those of critical strain energy release rates G... obtained in accordance with LEFM criteria under the condition of small-scale yielding, were made for various unfilled polypropylenes. blends of PP with ethylene-propylene random copolymer (EPR) and also with... 

Because of the pore structure of ZSM-5, the produced hydrocarbons are composed of low molecular species (4 carbons to about 20) which are in the gasoline, kerosene, and gas oil boiling range. In comparison, the carbon numbers of hydrocarbons produced only by thermal cracking range from 4 to 44. Polystyrene in the feedstock enhances the yield of ethylbenzene, toluene, and benzene, while producing gas that is predominantly propane/propylene. 

Homopolymers are made in a single reactor with propylene and catalyst. It is the stiffest of the three propylene types and has the highest tensile strength at yield. In the natural state (no colorant added) it is translucent and has excellent see through or contact clarity with liquids. In comparison to the other two types it has less impact resistance, especially below O C. 

These results are shown In Figure 8 and by making a comparison of Figures 9 and 10. Lobo et al (7) also found that olefins produced much more coke than paraffins. The greater coking ability of ethylene as compared to propylene Is caused primarily by the higher reactivity of ethylene somewhat higher yields of coke (based on the amount of olefin that reacts), however, occur with propylene as compared to ethylene. 

A maximum is clearly shown for each of the following propylene, ethylene, and butadiene. Comparison of Figures 7 and 9 denotes that the maximum yield of olefin is larger with crude oil of the higher K value, and it is attained by pyrolysis at conditions having a lower Ip value. 

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