low coke level fcc catalyst dyc-lc
high yield of coke in rfcc unit may lead to several problems, such as the yield of high value products will drop, increase of regeneration temperature will accelerate the hydrothermal deactivation of catalyst, and overload of regenerative catalyst cooler will reduce the feed quantity of raw material. hence, refiners and catalyst makers have always attached great importance to coke yield
in general, four types of deposited coke are identified in fcc catalysts: (1) catalytic coke - from condensation and dehydrogenation in catalytic cracking reactions. (2) catalyst-to-oil coke - hydrocarbons entrained in catalyst pores and not removed by the stripper. (3) contaminant coke - from dehydrogenation and condensation catalyzed by contaminant metal. (4) additive coke — from unconverted heavy molecules (including residual carbon and the precursor of coke like polycyclic aromatic hydrocarbons) already presented in the feed. besides the feed and design of units, all these types of coke formation are closely related to the nature of catalyst. for example, active matrix material is added in rfcc catalyst to enhance heavy oil conversion. however, non-selective reactions on this matrix, such as dehydrogenation and condensation, will increase dry gas and coke yield.
shandong duo you technology co. ltd., based on its own proprietary dyc technology platform, has developed dyc-lc series catalysts with lower coke and slurry yield through intensive effort on studying structure-activity relationship of fcc catalyst.
1、physical-chemical specification of dyc-lc catalyst
table 1 physical-chemical specification of dyc-lc catalyst
*catalyst steamed under 800oc/100% steam; standard light diesel feed, cracking temperature 460℃.
2、catalytic cracking results of dyc- lc catalyst on ace
taking m100 as a representative catalytic cracking feedstock, performance of dyc-lc and domestic competitive catalyst was tested on ace fixed fluidized bed introduced from america. because the results from ace are very similar to the industrial application results, product distribution of ace results can be used as a selection agent reference. the feedstock properties and tested results are shown in table 2 and table 3.
表 2 m100原料油性质
table 2 properties of m100 feedstock
as shown in table 2, the m100 feedstock contains low hydrogen and saturated hydrocarbons, high aromatics and resins, high contaminant metals and basic nitrogen, and is a feedstock which is hard to crack.
table 3 results of dyc-lc catalyst on ace unit
*catalyst steamed at 800℃/100% steam/17h;
table 3 shows that under the same reaction conditions, compared with competitive fcc catalyst, heavy oil conversion for dyc-lc catalyst is 0.87% higher, coke yield is 1.52% lower, gasoline lco yield and lpg gasoline lco yield is 1.34% and 2.22% higher respectively, while bottoms yield is 0.51% lower. the results show clearly that dyc-lc catalyst has better performance on both coke selectivity and bottoms cracking.
based on the results above, the following observations can be made: dyc-lc catalyst combines not only lower coke selectivity but also higher heavy oil conversion.