PTQ Q1 2023 Issue

Catalyst properties



Fresh surface area, m 2 /gm

150-250 0.35-0.4

PV, cc/gm

APS, micron ABD, gm/cc



Attrition Index, wt%


Table 1

phenomenon and reduces the gasoline range olefins. The cracking rates of gasoline olefins on ZSM-5 are higher than those of paraffins, so an increase in hydrogen transfer reduces the effectiveness of ZSM-5 additives. As explained, the synergistic alumina and Y-zeolite cracking of feed mol- ecules will provide maximum activity and higher gasoline range olefins for cracking on modified ZSM-5. The ratio of monomolecular to bimolecular for the catalyst * formulation is higher, indicating monomolecular reactions are the domi- nant catalyst * formulation. The paraffin-to-olefin ratio, a measure of hydrogen transfer reactions, is almost 50% less in the catalyst * formulation, indicating the catalyst design is selective towards light olefins. Experimental details Catalyst synthesis Synthesis of the proprietary catalyst * formulation included RE exchange with USY, surface modification of alumina to change the strength of the acid site, and modification of the ZSM-5 zeolite. The slurry containing various ingredi- ents was spray dried, as shown in Figure 4 , to produce the micro-spheroidal catalyst with the typical properties given in Table 1 . Slurry solid loading varies from 20-30%. The formed body is calcined at 500-600 o C for 2-4 hours. The catalytic cracking experiments were carried out in a custom-designed FCC pilot unit, as shown in Figure 5 . The gaseous products were analysed by Micro GC, and liquid products were analysed in LT SimDis. Conversion was obtained by the sum of yields of dry gas, LPG, gaso- line, and coke. Hydrotreated vacuum gas oil (VGO) was used as feedstock with a density of 0.9 g/cc, <500 ppm sulphur, and less than 0.1 wt% CCR. Using this feed, the tailor-made catalyst * formulation was subjected to catalytic cracking at temperatures of 550-560°C. The pilot results showed a C 3 = yield of 18.96% with gasoline RON >95 and olefin content >55%. The catalyst * formulation also acts as an additive in con - ventional FCC units. Refinery trials were taken at three

Figure 5 Custom designed FCC pilot unit

FCC units (see Figure 6 ) to assess the performance of the catalyst as an additive and commercial demonstration as a catalyst in one of India’s DCC units. Catalyst trial as an additive Field trial at FCC unit A: Trials were conducted by 10% inventory changeover over 1.5 months. Unit throughput was 100 m 3 /hr with 490 o C ROT, 0.88 g/cc feed density, 0.3 wt% sulphur, and 0.11 wt% CCR with 5.7 wt/wt unit cat/ oil. A test run was conducted to see the performance of catalyst * as an additive at 10% concentration. Performance of catalyst * showed a 0.6 wt% increase in LPG, 0.5 wt% increase in propylene, 0.6 unit increase in RON, and 0.2 wt% reduction bottoms with reference to the base case. Field trial at FCC unit B: Trials were conducted at FCC unit B by 15% inventory changeover over one month. Unit throughput was 130 m 3 /hr with 524 o C ROT, 0.918 g/cc feed density, 1.6 wt% sulphur, and 0.62 wt% CCR with 7.1 wt/wt unit cat/oil, with monthly average yields before and after the addition of catalyst as an additive at 15% con- centration. Performance of catalyst * showed a 0.32 wt% decrease in dry gas, 0.50 wt% increase in LPG, 0.54 wt% increase in propylene, 0.62 wt% increase in LCO, and 1 wt% reduction in bottoms with reference to the base case. In both FCC unit (A and B) field trials, C 3 = selectivity in LPG increased by 2.5 to 5 vol% from a base value of 34-35 vol%. Field trial at FCC unit C: Trials were conducted by 10% inventory changeover over two months in resid FCC unit. Unit throughput was 176-179 m 3 /hr with 520-525 o C ROT,

FCC unit A C = +0.6% RON = +0.6 units CLO = -0.2%

FCC unit B C = +0.54% LCO = +0.62% CLO = -1%

FCC unit C C = +0.31% RON = +0.2 units CLO = -0.25%

Figure 6 Delta yields with reference to base case


PTQ Q1 2023

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