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Frontiers of Chemical Science and Engineering

ISSN 2095-0179

ISSN 2095-0187(Online)

CN 11-5981/TQ

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Front. Chem. Sci. Eng.    2018, Vol. 12 Issue (1) : 9-23    https://doi.org/10.1007/s11705-017-1696-1
VIEWS & COMMENTS
A novel fluid catalytic cracking process for maximizing iso-paraffins: From fundamentals to commercialization
Youhao Xu(), Shouye Cui
Research Institute of Petroleum Processing (RIPP), Sinopec, Beijing 100083, China
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Abstract

The maximizing iso-paraffins (MIP) developed by RIPP has improved gasoline quality to meet the demand of motor gasoline specification. A concept that two different reaction zones include cracking zone and conversion zone is proposed as the fundamental of MIP by research on fluid catalytic cracking (FCC) reaction chemistry. Based on the concept, the MIP process is featured by applying a novel sequential two-zone riser in conjunction with proprietary catalyst and engineering technique. The developed MIP process can not only improve gasoline yield or gasoline plus propylene yields but also produce gasoline with a higher content of iso-paraffins and a lower content of sulfur. A minimum octane number loss is achieved when MIP gasoline is treated by downstream desulfurization technology (RSDS/S Zorb). The combination of MIP and RSDS/S Zorb processes creates a very competitive route, which is different from the technical route used by other developed countries, to upgrade the quality of motor gasoline with the lowest economic costs in China. In just one decade, the processing capacity of MIP units has accounted for about 60% of the domestic total processing capacity of FCC units. The MIP process is gradually becoming a new generation of FCC technology.
Keywords gasoline      iso-paraffins      FCC      desulfurization      octane number     
Corresponding Author(s): Youhao Xu   
Just Accepted Date: 10 November 2017   Online First Date: 02 February 2018    Issue Date: 26 February 2018
 Cite this article:   
Youhao Xu,Shouye Cui. A novel fluid catalytic cracking process for maximizing iso-paraffins: From fundamentals to commercialization[J]. Front. Chem. Sci. Eng., 2018, 12(1): 9-23.
 URL:  
https://academic.hep.com.cn/fcse/EN/10.1007/s11705-017-1696-1
https://academic.hep.com.cn/fcse/EN/Y2018/V12/I1/9
Fig.1  Progressive reductions of sulfur, olefins, benzene and aromatics in gasoline
Emission standards GB-17930-1999 GB-17930-2006 GB-17930-2006 GB-17930-2011 GB-17930-2013
? GB-II GB-III GB-IV GB-V
Sulfur/(g.g?1) ≯1000 ≯500 ≯150 ≯50 ≯10
Olefins/% ? ≯35 ≯30 ≯28 ≯25
Aromatics/% ≯40 ≯40 ≯40 ≯40 ≯40
Benzene/% ≯2.5 ≯2.5 ≯1.0 ≯1.0 ≯1.0
Oxygen/wt-% ? ≯2.7 ≯2.7 ≯2.7 ≯2.7
Tab.1  Main indicators of Chinese motor gasoline (GB-17930)
Fig.2  Reaction routes for catalytic cracking and conversion of hydrocarbons to produce iso-paraffins and aromatics
Fig.3  
Fig.4  
Paraffins C6 C16 C32
Carbenium ions C4 C6 C12 C4 C6 C12 C4 C6 C12
Energy barrier /(kJ·mol−1) 78.7 103.3 112.8 42.2 67.2 76.4 24.9 49.9 59.1
Tab.2  Reaction properties of the hydride transfer reactions of paraffins with different number of carbon atoms
Fig.5  
Fig.6  Change of each component concentration in gasoline with reaction depth □: iso-paraffin; ■ : olefin; ●: aromatics; ○: n-paraffin; ▲: naphthene
Fig.7  Schematic diagram of a MIP reactor
Catalysts REUSY REY
WHSV /h–1 8 16 24 8 16 24
Conversion /% 74.9 70.4 66.7 73.1 70.2 68.7
Coke yield /% 5.96 5.58 5.41 6.66 6.22 6.14
Gasoline olefins /% 25.8 31.5 31.1 22.6 25.6 25.1
Tab.3  Heavy oil cracking behavior on REUSY and REY catalystsa)
Fig.8  Deactivation of different zeolite catalysts with reaction times
Fig.9  SEM and TEM images of the novel mesopore matrix
Fig.10  XPS carbon spetra of coked catalysts obtained from different feedstocks
Fig.11  Aromatics yield of n-heptente cracking on ZRP zeolites
Zeolite Na2O /% UCS/ nm Crystallinity/% SBET/ (m2·g−1) VP / (mL·g−1)
REUSY 2.3 2.456 60.4 593 0.316
AIRY 2.0 2.456 63.6 662 0.355
Tab.4  Main differences in AIRY and REUSY
Fig.12  Cumulative pore volumes of the regenerated and spent catalysts obtained by a DFT model
Fig.13  Schematic diagrams of reaction-regeneration systems: (a) FCC, and (b) MIP
Unit GQ Branch company JJ Branch Company JJ Branch Company BL Branch Company
Technology MIP FCC MIP-CGP FCC MIP-CGP MIP-DCR MIP-CGP MIP-LTG
Feedstock properties
Density/g·cm−3 0.8966 0.8967 0.9097 0.8951 0.9205 0.9256 0.8953 0.8953
CCR/% 4.68 4.00 4.59 3.86 1.4 1.58 4.8 4.5
Hydrogen content/% 12.86 12.80 12.58 12.78 12.4 12.4 12.81 12.70
Product distribution/%
Dry gas 2.88 3.79 3.45 3.72 2.52 2.13 3.18 3.24
LPG 14.63 15.44 27.37 19.11 14.56 14.94 28.89 28.42
Gasoline 49.28 44.14 38.19 40.66 35.23 36.39 42.52 44.03
LCO 21.22 22.57 16.30 21.89 36.08 34.85 12.67 11.74
Slurry 3.04 4.64 5.12 5.22 4.43 4.78 3.26 3.64
Coke 8.64 8.92 9.09 8.90 6.59 6.32 9.06 8.51
Loss 0.31 0.50 0.48 0.50 0.59 0.59 0.42 0.42
Sum 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00
Total liquid 85.13 82.15 81.86 81.66 85.86 86.17 84.07 84.62
Gasoline properties
Olefin content/% 34.11 43.10 13.4 41.1 34.4 35.9 28.2 28.7
RON 88.8 89.4 93.5 91.6 94.4 94.2 94.2 94.5
MON 80.2 79.2 83.9 ? 80.9 80.9 82.3 82.8
STC/% 5.80 10.40 7.30 9.52 ? ? 5.86 5.97
Tab.5  Calibration results of several typical MIP processes
Fig.14  Evolvement of reactor types of the catalytic cracking process in 80 years
Type of technology VGO FCC VGO FCC Variation RFCC Residue MIP Variation
Type of reactor Dense-phase fluidized bed a) Risera) riserb) Two-zone riserb)
Catalyst Amorphous silica-alumina Sieve Sieve Sieve
Reaction time long short short long
Feed properties
Density (20 °C)/g·cm−3 0.8410 0.8722 0.8967 0.8966
CCR/% 0.15 0.13 4.0 4.68
Operation parameters
Temperature
(riser outlet)/°C		 467 493 +26 515 497
Recycling ratio/% 100 82 −18 5.5 1.15 −4.35
Product distribution/%
Dry gas 1.48 1.42 −0.06 3.79 2.88 −0.91
LPG 11.6 10.92 −0.68 15.44 14.63 −0.81
Gasoline 44.20 49.63 +5.43 44.14 49.28 5.14
LCO 35.50 31.30 −4.20 22.57 21.22 −1.35
Slurry 4.64 3.04 −1.60
Coke 6.00 5.35 −0.65 8.92 8.64 −0.28
Loss 1.22 1.38 0.50 0.31
Sum 100.00 100.00 100.00 100.00
Conversion 64.50 68.70 +4.20 72.79 75.74 +2.95
Total liquid 92.34 92.65 +0.31 82.15 85.13 +2.98
Gasoline properties
Olefins/% 54.8 29.6 −25.2 43.1 34.3 −8.8
Aromatics/% 8.4 10.6 2.2 14.8
MON 82.2 77.3 −4.9 79.2 80.2 +1.0
Tab.6  Product distribution and properties of different FCC processes
Type of gasoline MIP FCC Technology type MIP FCC
Compositions by mass/% Olefins compositions/% 25.07 40.78
N-paraffins 4.93 4.74 N-olefin-1 1.16 1.93
Iso-paraffins 31.18 23.91 N-olefin-2 6.10 8.68
Olefins 25.07 40.78 N-olefin-3 1.04 2.94
Naphthenes 7.31 7.31 Mono-branched olefins 6.05 10.30
Aromatics 29.61 22.24 Di-branched olefins 7.30 9.70
Benzene 0.88 0.78 Multi-branched olefins 0.09 0.30
RON 92.9 93.0 Cyclic olefins 2.85 5.89
MON 82.0 81.5 Diene+ triene+ alkyne 0.47 1.03
Iso-paraffins /N-paraffins 6.32 5.04 Iso-olefins/N-olefins 1.62 1.48
RBA 2.97 3.51 Di-branched olefins/Mono-branched olefins 1.20 0.94
Tab.7  Gasoline compositions of MIP and FCC
Company FCC/(Mt·a−1) MIP/(Mt·a−1) Sum
Number of units Capacity Proportion Number of units Capacity Proportion Number of units Capacity
SINOPEC 27 23.30 30.0 31 54.25 70.0 58 77.55
PetroChina 28 30.30 62.0 12 18.60 38.0 40 48.90
CNOOC 4 3.70 31.6 4 8.00 68.4 8 11.70
Yanchang Petroleum 1 1.00 13.5 5 6.40 86.5 6 7.40
Sinochem 0 0 0.0 1 3.50 100.0 1 2.50
Other refinerya) 2 1.80 2 1.80
Total 53 90.15
Other refineryb) 30 14.36 46.2 14 b) 14.90 53.8 44 29.26
Total 92 75.06 41.7 67 105.05 58.3 159 180.11
Tab.8  Statistics of number of units built and processing capacity of Chinese FCC unit
Pathway 1 (MIP+ GDS+ALy+MTBE) Pathway 2 (FCC+ GDS+ALy+MTBE)
Yield/
wt-%		 RON Olefins/
vol- %		 Sulfur/
µg·g−1		 Yield/
wt-%		 RON Olefins/vol-% Sulfur/
µg·g−1
Alkylate Gasoline 7.61 94.5 6.11 94.5
Gasoline 40.76 92.5 29.4 9.0 38.21 90.3 32.0 9.0
Blended Gasoline 48.37 ~92.8 <25 <10 44.32 ~90.8 ~27.5 <10
MTBE 5.40 121 5.01 121
Blended Gasoline 53.77 95.6 <25 <10 49.33 93.8 ~24.7 <10
Tab.9  Yields and properties of blended gasoline produced by two pathways
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