Process for converting naphtha

Abstract

A process for converting naphtha, lower olefin, light aromatic hydrocarbon, and gasoline with a high octane number by combining catalytic cracking of naphtha with steam cracking of lower alkane and catalytic cracking of higher alkanes and higher olefins. The process increases the yield of product with high value and significantly decreases the yield of low value product. At the same time, the power consumption is decreased as a whole since most reactants are converted in catalytic cracking at a lower temperature.

Claims

1. A process for converting naphtha, the process comprising the steps of: a) sending a feed that contains naphtha into a first reaction zone to contact and react with a catalyst that contains a molecular sieve at a reaction temperature of 580 C. to 700 C. to produce reaction products, and separating the reaction products to obtain a material flow I and a product I; b) sending steam and the material flow I obtained in step a) into a second reaction zone to undergo a steam cracking reaction at a reaction temperature of 780 C. to 870 C., and obtaining a product III after the reaction; wherein the material flow I comprises alkanes with a carbon atom number of 2 to 5, wherein the alkanes with a carbon atom number of 2 to 5 comprise ethane, propane, butanes and pentanes; wherein the product I comprises alkenes with a carbon atom number of 2 to 12, aromatic hydrocarbons with a carbon atom number of 6 to 12, and alkanes with a carbon atom number of 6 to 12; and wherein the product III comprises lower alkenes with a carbon atom number of 2 to 4 and aromatic hydrocarbons with a carbon atom number of 6 to 8.

2. The process according to claim 1, wherein the reaction temperature of the first reaction zone in step a) is from 640 C. to 680 C.

3. The process according to claim 1, wherein the feed in step a) further comprises steam, and the weight ratio of steam to naphtha in the feed is from greater than 0 to 1.5.

4. The process according to claim 1, wherein, in the catalyst that contains a molecular sieve in step a), the molecular sieve is H-ZSM-5 molecular sieve.

5. The process according to claim 1, wherein, in the catalyst that contains a molecular sieve in step a), the molecular sieve is a molecular sieve obtained through modification with a lanthanide, phosphorus, or both.

6. The process according to claim 1, wherein, in step a) the catalyst that contains a molecular sieve, the molecular sieve comprises silica and alumina, and the molar ratio of the silica to the alumina of the molecular sieve is 20 to 200.

7. The process according to claim 1, wherein the weight ratio of steam and the material flow I entering the second reaction zone in step b) is 0.2 to 0.5; the temperature range of the second reaction zone is from 800 C. to 850 C.; and the retention time of steam and the material flow I in the second reaction zone is 0.2 s to 0.5 s.

8. A process for converting naphtha, the process comprising the steps of: a) sending a feed that contains naphtha into a first reaction zone to contact and react with a catalyst that contains a molecular sieve at a reaction temperature of 580 C. to 700 C. to produce reaction products, and separating the reaction products to obtain a material flow I, a material flow II, and a product II; b) sending steam and the material flow I obtained in step a) into a second reaction zone to undergo a steam cracking reaction at a reaction temperature of 780 C. to 870 C., and obtaining a product III after the reaction; c) returning the material flow II obtained in step a) to the first reaction zone; wherein the material flow I comprises alkanes with a carbon atom number of 2 to 5, wherein the alkanes with a carbon atom number of 2 to 5 comprise ethane, propane, butanes and pentanes; wherein the material flow II comprises alkanes with a carbon atom number of 6 to 12 and alkenes with a carbon atom number of 5 to 12; wherein the product II comprises lower alkenes with a carbon atom number of 2 to 4 and aromatic hydrocarbons with a carbon atom number of 6 to 8; and wherein the product III comprises lower alkenes with a carbon atom number of 2 to 4 and aromatic hydrocarbons with a carbon atom number of 6 to 8.

9. The process according to claim 2, wherein the weight hourly space velocity of naphtha in the feed to the first reaction zone in step a) is 0.5 h.sup.1 to 2.5 h.sup.1.

10. The process according to claim 8, wherein the feed in step a) further comprises steam, and the weight ratio of steam to naphtha in the feed is from greater than 0 to 1.5.

11. The process according to claim 8, wherein, in the catalyst that contains a molecular sieve in step a), the molecular sieve is a H-ZSM-5 molecular sieve.

12. The process according to claim 8, wherein, in the catalyst that contains a molecular sieve in step a), the molecular sieve is a molecular sieve obtained through modification with a lanthanide, phosphorus, or both.

13. The process according to claim 8, wherein, in the catalyst that contains a molecular sieve in step a), the molecular sieve is a molecular sieve modified with lanthanum and phosphorus, and wherein the mass percent of lanthanum in the modified molecular sieve is 6-12% as the oxide La.sub.2O.sub.3 and the mass percent of phosphorus in the modified molecular sieve is 3-10% as the oxide P.sub.2O.sub.5.

14. The process according to claim 8, wherein in step a) the catalyst that contains a molecular sieve comprises alumina and silica, and wherein the molar ratio of silica to alumina of the molecular sieve is 20 to 200.

15. A process for converting naphtha, the process comprising the steps of: a) sending a feed that contains naphtha into a first reaction zone to contact and react with a catalyst that contains a molecular sieve at a reaction temperature of 580 C. to 700 C. to produce reaction products, and separating the reaction products to obtain a material flow I and a product I; b) sending steam and the material flow I obtained in step a) into a second reaction zone to undergo a steam cracking reaction at a reaction temperature of 780 C. to 870 C., and obtaining a product III after the reaction; wherein the material flow I comprises alkanes with a carbon atom number of 2 to 5; wherein the product I comprises alkenes with a carbon atom number of 2 to 12, aromatic hydrocarbons with a carbon atom number of 6 to 12, and alkanes with a carbon atom number of 6 to 12; and wherein the product III comprises lower alkenes with a carbon atom number of 2 to 4 and aromatic hydrocarbons with a carbon atom number of 6 to 8, wherein, in the catalyst that contains a molecular sieve in step a), the molecular sieve is a molecular sieve modified with lanthanum and phosphorus, and wherein the mass percent of lanthanum in the modified molecular sieve is 6-12% as the oxide La.sub.2O.sub.3 and the mass percent of phosphorus in the modified molecular sieve is 3-10% as the oxide P.sub.2O.sub.5.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a flow chart of an implementation manner of the present application.

(2) FIG. 2 is a flow chart of an implementation manner of the present application.

(3) FIG. 3 is a diagram of changes to lower alkenes in the reaction products vs. reaction time when there is no steam in the feed onto a catalyst CAT-2# in Example 7.

(4) FIG. 4 is a diagram of changes to lower alkenes in the reaction products vs. reaction time on a catalyst CAT-1# in Example 8.

(5) FIG. 5 is a diagram of changes to lower alkenes in the reaction products vs. reaction time on the catalyst CAT-2# in Example 9.

(6) FIG. 6 is a diagram of changes to lower alkenes in the reaction products vs. reaction time on a catalyst CAT-3# in Example 10.

DETAILED DESCRIPTION OF THE INVENTION

(7) The present application will be described in detail below with reference to examples, but the present application is not limited to these examples.

(8) Unless specifically described, the raw materials and catalysts in examples of the present application were all purchased commercially, wherein the ZSM-5 molecular sieve was purchased from the Catalyst Factory of Nankai University. The composition of naphtha used in implementation of the present application is shown in Table 1 below:

(9) TABLE-US-00001 TABLE 1 Normal Aromatic Name of raw alkanes Isoalkanes Cycloalkanes hydrocarbons material (wt %) (wt %) (wt %) (wt %) Naphtha (IBP- 41.04 24.23 15.26 14.49 150 C.) Naphtha (IBP- 34.97 29.31 28.12 7.60 180 C.)

(10) The analytical method in the examples of the present application is as follows:

(11) Reaction products are analyzed by online GC. The GC is Agilent 7890A and detection is performed with Agilent HP-5 capillary columns.

(12) The method for calculating yield in the examples of the present application is as follows:
Yield=produced amount of a target product/amount of fed naphtha100%
The method for calculating selectivity of (ethylene+propylene+butylene) in the examples of the present application is as follows:
Selectivity of (ethylene+propylene+butylene)=(ethylene+propylene+butylene)/(hydrogen+hydrocarbons with a carbon atom number of 1 to 4)100%

(13) In the examples of the present application, the yield and selectivity are all calculated on a weight basis.

Example 1 Preparation of the Catalyst CAT-1#

Preparation of a Modified Molecular Sieve Z-1#

(14) The modified molecular sieve is prepared with the immersion method, specifically: immersing 84 g of a hydrogen-type ZSM-5 molecular sieve having a silicon to aluminum ratio (molar ratio) SiO.sub.2/Al.sub.2O.sub.3=50 in 100 ml of an La(NO.sub.3).sub.3 solution with a concentration of 0.74 mol/L, drying in an oven at 120 C., baking at 550 C., then immersing the baked solid in 100 g of a phosphoric acid solution with a concentration of 4 wt %; further drying in an oven at 120 C., baking at 550 C., and obtaining a modified molecular sieve marked as Sample Z-1#. In the Sample Z-1#, the mass percent of La.sub.2O.sub.3 is 12%, and the mass percent of P.sub.2O.sub.5 is 4%.

Preparation of the Catalyst CAT-1#

(15) Mixing 75 g of the Sample Z-1# and 25 g of aluminum oxide, adding 30 ml 3% diluted nitric acid, stirring and kneading, and extruding to mold; further drying in an oven at 120 C., baking at 650 C., and obtaining a molded catalyst marked as the catalyst CAT-1#. In the catalyst CAT-1#, the mass percent of the Sample Z-1# is 75%, and the mass percent of aluminum oxide is 25%.

Example 2 Preparation of the Catalyst CAT-2#

Preparation of a Modified Molecular Sieve Z-2#

(16) Immersing 84 g of a hydrogen-type ZSM-5 molecular sieve having a silicon to aluminum ratio (molar ratio) SiO.sub.2/Al.sub.2O.sub.3=50 in 100 ml of an La(NO.sub.3).sub.3 solution with a concentration of 0.74 mol/L, drying in an oven at 120 C., baking at 550 C., then immersing the baked solid in 100 g of a phosphoric acid solution with a concentration of 4 wt %; further drying in an oven at 120 C., baking at 550 C., and obtaining a modified molecular sieve marked as Sample Z-2#. In the Sample Z-2#, the mass percent of La.sub.2O.sub.3 is 12%, and the mass percent of P.sub.2O.sub.5 is 4%.

Preparation of the Catalyst CAT-2#

(17) Mixing 80 g of the Sample Z-2# and 20 g of aluminum oxide, adding 40 ml 3% diluted nitric acid, stirring and kneading, and extruding to mold; further drying in an oven at 120 C., baking at 650 C., and obtaining a molded catalyst marked as the catalyst CAT-2#. In the catalyst CAT-2#, the mass percent of the Sample Z-2# is 80%, and the mass percent of aluminum oxide is 20%.

Example 3 Preparation of the Catalyst CAT-3#

Preparation of a Modified Molecular Sieve Z-3#

(18) Immersing 87 g of a hydrogen-type ZSM-5 molecular sieve having a silicon to aluminum ratio (molar ratio) SiO.sub.2/Al.sub.2O.sub.3=100 in 100 ml of an La(NO.sub.3).sub.3 solution with a concentration of 0.56 mol/L, drying in an oven at 120 C., baking at 550 C., then immersing the baked solid in 100 g of a phosphoric acid solution with a concentration of 4 wt %; further drying in an oven at 120 C., baking at 550 C., and obtaining a modified molecular sieve marked as Sample Z-3#. In the Sample Z-3#, the mass percent of La.sub.2O.sub.3 is 9%, and the mass percent of P.sub.2O.sub.5 is 4%.

Preparation of the Catalyst CAT-3#

(19) Mixing 80 g of the Sample Z-3# and 20 g of aluminum oxide, adding 80 ml 3% diluted nitric acid, stirring and kneading, and extruding to mold; further drying in an oven at 120 C., baking at 650 C., and obtaining a molded catalyst marked as the catalyst CAT-3#. In the catalyst CAT-3#, the mass percent of the Sample Z-3# is 80%, and the mass percent of aluminum oxide is 20%.

Examples 4-6 Reaction of Naphtha on the Catalyst CAT-2#

(20) The reaction flow is shown in FIG. 1. First, sending the feed of naphtha (IBP180 C.) and steam into a first reaction zone, the first reaction zone is a fixed bed reactor filled with 10 g of the catalyst CAT-2#, reacting at a reaction temperature of 670 C., and separating the reaction products obtained from the reaction in the first reaction zone to obtain a material flow I, a product I, and a byproduct I, wherein the material flow I comprises alkanes with a carbon atom number of 2 to 5, the product I comprises alkenes with a carbon atom number of 2 to 12, aromatic hydrocarbons with a carbon atom number of 6 to 12, and alkanes with a carbon atom number of 6 to 12, and the remainder is the byproduct I. Sending the material flow I and steam into a steam cracking reactor in a second reaction zone to undergo a steam cracking reaction. The second reaction zone is a tube furnace reactor. Mixing the obtained product III with the chemical products in the product I obtained from the fixed bed reactor of the first reaction zone, wherein the product III obtained from the second reaction zone comprises lower alkenes with a carbon atom number of 2 to 4 and aromatic hydrocarbons with a carbon atom number of 6 to 8, and the remainder is the byproduct III.

(21) See Table 2 for reaction conditions and yields.

(22) TABLE-US-00002 TABLE 2 Conditions and yields of reactions of naphtha on the catalyst CAT-2# Examples 4 5 6 Reaction Catalyst CAT-2.sup.# CAT-2.sup.# CAT-2.sup.# conditions for the Reaction temperature/ C. 640 670 680 first reaction Weight hourly space velocity (WHSV) of naphtha/ 1.0 1.2 1.4 zone h.sup.1 0.6 0.4 0.2 Steam/naphtha (weight ratio) 0.3 0.4 0.5 Reaction Steam/material flow I (weight ratio) 820 840 850 conditions for the Temperature/ C. 0.2 0.4 0.5 second reaction Retention time/s 46.21 49.51 48.94 zone First reaction Gas products, total 53.33 50.02 50.57 yield, total.sup.a (%) Liquid products, total 0.46 0.46 0.49 Coke Gas products and Hydrogen 0.37 0.37 0.39 yields in the first Methane 2.95 3.89 4.04 reaction zone.sup.b Ethylene 10.43 11.67 11.61 (%) Propylene 18.37 18.06 17.22 Butylene Ethane Propane Butane Liquid products 2-methyl butane and yields in the Pentane first reaction Hexane zone (%) Heptane Octane 6.52 6.45 6.63 Nonane 2.95 3.80 3.94 2-methyl pentane 2.77 3.33 3.44 3-methyl-pentane 1.85 1.94 1.67 methyl-cyclopentane 0.47 0.49 0.75 2-methyl-hexane 0.1 0.1 0.2 2,3-dimethyl-pentane 5.00 3.01 3.55 3-methyl-hexane 1.08 1.25 1.37 1,3-dimethyl-cyclopentane 1.18 1.34 1.31 1,2-dimethyl-cyclopentane 0.9 0.86 0.82 methyl-cyclohexane 0.73 0.76 1.13 2,4-dimethyl-hexane 0.40 0.46 0.61 1,2,4-trimethyl-cyclopentane 0.25 0.32 0.39 1,2,3-trimethyl-cyclopentane 0.42 0.48 0.55 1,1,2-trimethylcyclopentane 0.35 0.37 0.42 3-methyl-heptane 0.69 0.77 0.89 cis 1,3-dimethyl-cyclohexane 0.20 0.24 0.26 cis 1,4-dimethylcyclohexane 0.98 1.11 1.21 1,1-dimethyl-cyclohexane 1.86 2.08 2.34 1-ethyl I-2 methyl-cyclopentane 0.23 0.25 0.26 0.46 0.47 0.48 0.54 0.57 0.66 0.24 0.38 0.39 0.61 0.63 0.64 1.80 1.76 1.47 0.26 0.23 0.23 0.22 0.35 0.34 0.36 trans 1,2-dimethyl-cyclohexane 0.85 0.80 0.78 cis 1,4-dimethyl-cyclohexane 0.29 0.29 trans 1,3-dimethyl-cyclohexane 0.28 2,4-dimethyl-heptane 0.26 0.25 cis 1,2-dimethyl-cyclohexane 0.20 ethyl-cyclohexane 1.23 1.14 1.11 1,1,3-trimethylcyclohexane 1.39 1.21 1.15 3,5-dimethyl-heptane 0.30 2,5-dimethyl-heptane 0.41 0.31 1-ethyl-2-methyl-cyclohexane 0.24 0.21 1,2,4-trimethyl-cyclohexane 0.51 0.44 0.38 2,3-dimethyl-heptane 0.71 0.61 0.53 3-methyl-octane 0.30 1,1,2-trimethyl-cyclohexane 0.12 1-ethyl-3-methylcyclohexane 0.57 0.47 0.42 1-ethyl-4-methyl-cyclohexane 0.19 cis bicyclononane 0.27 0.20 0.00 2,6-dimethyl-octane 0.28 benzene 1.26 2.02 2.51 toluene 3.97 5.63 5.96 p-xylene 3.04 3.21 3.07 o-xylene 1.02 1.10 1.00 ethylbenzene 0.21 0.24 0.00 1-ethyl-3-methyl-benzene 0.20 0.23 1,2,3-trimethyl-benzene 0.34 naphthalene 0.25 0.00 0.00 Others (content <0.5%) 3.60 2.48 1.09 Statistics on ethylene + propylene + butylene (%) 35.32 36.26 35.47 yields of main Selectivity of (ethylene + propylene + butylene) (%) 76.43 73.24 72.49 products in the propylene/ethylene first reaction BTX.sup.c (%) 1.76 1.55 1.48 zone (%) ethylene + propylene + butylene + BTX (%) 8.86 11.39 12.3 ethane + propane + butane + pentane (%) 44.18 47.65 47.77 N-alkanes with a carbon atom number C6 21.22 21.22 21.26 Isoalkanes and cycloalkanes 8.16 6.46 7.05 Other aromatic hydrocarbons and trace 17.89 16.94 17.5 components 4.77 3.08 1.51 Products and ethylene 8.46 8.64 8.67 yields in the propylene 3.4 3.23 3.22 second reaction butylene 0.39 0.38 0.38 zone (%) butadiene 0.75 0.72 0.73 BTX 0.37 0.41 0.43 Total yields of lower alkenes + BTX (%) 57.55 61.03 61.2 the first and gasoline with high octane number 30.81 26.48 26.06 second reaction Total 88.38 87.51 87.26 zones (%) Note .sup.aall yields in the table are percent yields by weight. Note .sup.bBTX refers to light aromatic hydrocarbon, comprising benzene, toluene and xylene. Note .sup.cC.sub.6-12 alkanes refer to alkanes with a carbon atom number of 6 to 12.

(23) From the data in Table 2, it can be seen that, at a reaction temperature of 670 C., naphtha goes through one catalytic cracking reaction, and alkanes with a carbon atom number from 2 to 5 in the products undergo steam cracking and recycling. The total yield of the final chemical products (lower alkenes+BTX) and gasoline with high octane number (other liquid products after BTX is removed) reaches up to 87 to 88%.

Example 7 Reaction on the Catalyst CAT-2# in the First Reaction Zone without Steam

(24) The reaction flow is the same as that in Example 4, except that no steam is added in the first reaction zone. The reaction flow is shown in FIG. 1. The reaction results of naphtha (IBP-180 C.) at 670 C. are listed in Table 3.

(25) TABLE-US-00003 TABLE 3 Conditions and yields of reactions of naphtha on the catalyst CAT-2# with no addition of water Example 7 Catalyst CAT-2.sup.# Reaction conditions Temperature/ C. 670 for the first reaction Weight hourly space velocity 1.6 zone (WHSV) of naphtha/h.sup.1 Steam/naphtha (w/w) 0 Reaction conditions ratio of the material flow I to steam 0.4 for the second Temperature/ C. 820 reaction zone Retention time/s 0.3 Total reaction yield.sup.a Gas products, total (%) 57.99 (%) Liquid products, total (%) 41.46 Coke (%) 0.55 Gas products and Hydrogen (%) 0.83 yields in the first Methane (%) 5.87 reaction zone (%).sup.b Ethylene (%) 12.84 Propylene (%) 20.18 Butylene (%) 7.26 Ethane (%) 4.59 Propane (%) 4.04 Butane 2.39 Total yield of gas products 57.99 Liquid products in 2-methyl butane 0.65 the first reaction zone Pentane 9.2 (%) Hexane 2.07 Heptane 0.78 Octane 0.46 2-methyl pentane 0.68 3-methyl pentane 0.42 methyl-cyclopentane 0.21 2,3-dimethyl-pentane .32 3 methyl-hexane .53 trans 1,2-dimethyl-cyclopentane methyl-cyclohexane 1,2,4-trimethyl-cyclopentane 0.93 1,2,3-trimethyl-cyclopentane 1.36 3-methyl-heptane 0.30 cis 1,3-dimethyl-cyclohexane 0.40 1-ethyl-2-methyl-cyclopentane 0.32 trans 1,2-dimethyl-cyclohexane 0.76 ethyl-cyclohexane 0.18 1,1,3-trimethylcyclohexane 0.43 2,3-dimethyl heptane 0.48 benzene 0.53 toluene 0.27 p-xylene 4.68 o-xylene 7.65 ethylbenzene 3.49 1,2,3-trimethyl benzene 1.13 naphthalene 0.29 Others (content <0.5%) 0.32 Statistics on main ethylene + propylene + butylene (%) 0.17 products in the first Selectivity of (ethylene + 2.57 reaction zone (%) propylene + butylene) (%) 40.28 propylene/ethylene 69.46 BTX.sup.c (%) ethylene + propylene + butylene + 1.57 BTX (%) 16.97 C2-C5 alkanes that can be 57.26 cracked by steam C6, normal alkanes 20.77 Isoalkanes and cycloalkanes 3.31 Other aromatic hydrocarbons and 8.12 trace components 3.31 Products and yields ethylene 5.36 in the second reaction propylene 1.34 zone (%) butylene 0.32 butadiene 0.66 BTX 0.42 Total yields of the lower alkenes + BTX (%) 65.36 first and second gasoline with high octane number 14.74 reaction zones (%) Total 80.1 Note .sup.aall yields in the table are percent yields by weight. Note .sup.bBTX refers to light aromatic hydrocarbon, comprising benzene, toluene and xylene. Note .sup.cC.sub.6-12 alkanes refer to alkanes with a carbon atom number of 6 to 12.

(26) It can be seen that, when no steam is added in the catalytic cracking reaction in the first reaction zone, the selectivity is lowered to a degree and the methane yield increases to a degree, but the yield of lower alkenes+BTX in the catalytic cracking products increases. This is because the catalyst activity is higher and the conversion rate of reactants is increased when there is no steam. The decreasing selectivity of the catalytic cracking reaction leads to the decreased total yield of the target products, which is still up to 80%.

(27) See FIG. 3 for changes to lower alkenes in the catalytic reaction products vs. reaction time.

Examples 8-10 Reactions of Naphtha on Different Catalysts Using Catalytic Cracking and Recycling

(28) The reaction flow is shown in FIG. 2. First, sending the feed of naphtha (IBP150 C.) and steam into a first reaction zone. In Example 8, Example 9 and Example 10, the first reaction zones are filled, respectively, with 10 g of the catalyst CAT-1#, the catalyst CAT-2#, and the catalyst CAT-3# prepared in Examples 1, 2, and 3, all of which are fixed bed reactors. The reaction products obtained from the reaction in the first reaction zone are separated to obtain a material flow I, a material flow II, a product II, and a byproduct II, wherein the material flow I comprises alkanes with a carbon atom number of 2 to 5, the material flow II comprises alkanes with a carbon atom number of 6 to 12 and alkenes with a carbon atom number of 5 to 12, the product II comprises lower alkenes with a carbon atom number of 2 to 4 and aromatic hydrocarbons with a carbon atom number of 6 to 8, and the remainder is the byproduct II. Returning the material flow II to the fixed bed reactors in the first reaction zone to continue the catalytic cracking reaction. Sending the material flow I and steam into a steam cracking reactor in a second reaction zone to undergo a steam cracking reaction. The second reaction zone is a tube furnace reactor, and both the obtained product III and the product II obtained from the fixed bed reactor of the first reaction zone are used as chemical products, wherein the product III obtained from the second reaction zone comprises lower alkenes with a carbon atom number of 2 to 4 and aromatic hydrocarbons with a carbon atom number of 6 to 8, and the remainder is the byproduct III.

(29) See Table 4 for reaction temperature, weight ratio of water to naphtha (IBP150 C.), and weight hourly space velocity of naphtha in the feed, and other conditions are the same as those in Example 4. The results of reactions of naphtha (IBP150 C.) on different catalysts are listed in Table 4.

(30) Table 4 Conditions and yields of reactions on different catalysts in Examples 8-10

(31) TABLE-US-00004 TABLE 4 Conditions and yields of reactions on different catalysts in Examples 8-10 Examples 8 9 10 Reaction Catalyst CAT-1.sup.# CAT-2.sup.# CAT-3.sup.# conditions for the Temperature/ C. 640 670 680 first reaction zone Weight hourly space velocity (WHSV) of naphtha/h.sup.1 0.8 0.8 0.8 WHSV of steam/h.sup.1 0.8 1.0 1.5 Reaction Steam/material flow I (weight ratio) 1 0.35 0.4 conditions for the Temperature/ C. 800 820 840 second reaction zone Retention time/s 0.25 0.3 0.35 Reaction yields in Gas products, total (%) 58.77 68.1 55.36 the first reaction Liquid products, total (%) 40.95 31.52 44.35 zone.sup.a Coke (%) 0.28 0.38 0.42 Gas products and Hydrogen (%) 0.37 0.38 0.29 yields in the first Methane (%) 3.4 3.83 3.25 reaction zone (%).sup.b Ethylene (%) 13.62 16.46 11.95 Propylene (%) 30.3 33.2 29.3 Butylene (%) 8.0 8.9 7.7 Ethane (%) 4.42 4.69 3.82 Propane (%) 4.14 4.59 3.44 Butane 2.58 2.39 2.39 Liquid products 2-methyl butane 0.23 0.12 0.43 and yields in the Pentane 8.39 8.56 8.59 first reaction zone Hexane 1.39 1.46 1.93 (%) Heptane 1.00 044 1.57 Nonane 0.62 0.25 0.97 dimethyl pentane 0.52 0.36 0.84 trimethyl pentane 0.34 0.23 0.53 dimethyl hexane 0.42 0.25 0.61 2,3-dimethyl-pentane 0.34 0.27 0.35 trimethyl hexane 0.60 0.36 0.77 triethyl pentane 0.12 1,2-dimethyl cyclopentane 0.31 0.24 0.31 methyl-cyclohexane 0.61 0.39 0.61 2-methyl-3-ethyl pentane 0.47 0.24 0.34 1,2,4-trimethyl cyclopentane 0.20 0.15 0.19 1,2,3-trimethyl cyclopentane 0.17 0.21 3-ethyl-2-methyl pentane 0.36 0.37 0.48 3-methyl heptane 0.72 0.42 0.82 cis 1,3-dimethyl cyclohexane 0.44 0.38 0.52 1-ethyl-2-methyl cyclopentane 0.28 0.20 0.28 1,2-dimethyl cyclohexane 0.24 0.18 0.23 2,4-dimethyl heptane 0.93 0.34 1.49 2,3,4-trimethyl hexane 0.28 0.16 0.22 ethyl cyclohexane 0.84 0.55 0.84 1,2,3-trimethyl cyclohexane 0.43 0.28 0.37 2,5-dimethyl heptane 0.56 0.39 0.55 2,3-dimethyl heptane 0.84 0.49 0.76 3-ethyl heptane 0.18 0.13 3-methyl octane 0.38 0.19 0.49 1-ethyl-3-methylcyclohexane 0.40 0.25 0.36 2,6-dimethyl octane 0.47 0.32 0.47 2-methyl-3-ethyl heptane 0.42 0.29 0.40 benzene 1.54 1.45 1.67 toluene 4.59 3.38 4.46 p-xylene 3.96 2.77 3.98 o-xylene 1.58 1.18 1.54 1-ethyl-2-methyl benzene 0.69 0.39 0.49 1,2,3-trimethyl benzene 0.27 0.17 0.28 1-ethyl-4-methyl benzene 0.45 0.25 0.33 1,2,4-trimethyl benzene 0.49 0.34 0.45 3-methyl styrene 0.22 0.17 0.70 piperidine 0.41 0.19 0.37 Others (content <0.5%) 3.93 2.65 4.36 Statistics on main ethylene + propylene + butylene (%) 43.76 52.12 42.17 products Selectivity of (ethylene + propylene + butylene) (%) 74.46 76.53 76.17 propylene/ethylene 1.65 1.64 1.86 BTX.sup.b (%) 11.68 8.80 11.66 ethylene + propylene + butylene + BTX (%) 55.45 60.92 53.83 C2-C5 alkanes that can be cracked by steam 19.75 20.35 18.66 C6, normal alkanes 3.01 2.15 5.04 Isoalkanes and cycloalkanes 11.58 7.72 13.04 Other aromatic hydrocarbons and trace components 6.07 4.17 5.6 Products and ethylene 8.20 8.47 7.70 yields in the propylene 2.83 2.90 2.74 second reaction butylene 0.30 0.30 0.30 zone (%) butadiene 0.62 0.63 0.60 BTX 0.40 0.41 0.40 Total Chemical products from steam cracking 12.35 12.71 11.74 Products of ethylene 2.04 1.38 2.52 secondary catalytic propylene 4.38 2.96 5.41 cracking of C.sub.6-12 butylene 1.17 0.79 1.44 alkanes.sup.c (%) BTX 1.60 1.09 1.98 Total Chemical products from secondary catalytic cracking 9.19 6.21 11.35 Total yields of the ethylene 23.86 26.31 22.17 first and second propylene 37.51 39.06 37.45 reaction zones (%) butylene 9.47 9.99 9.44 butadiene 0.62 0.63 0.60 BTX 13.68 10.3 14.04 Total 85.14 86.29 83.7 Note .sup.aall yields in the table are percent yields by weight. Note .sup.bBTX refers to light aromatic hydrocarbon, comprising benzene, toluene and xylene. Note .sup.cC.sub.6-12 alkanes refer to alkanes with a carbon atom number of 6 to 12.

(32) After the catalytic cracking reaction on naphtha in the first reaction zone, the steam cracking and recycling of the material flow I and the catalytic recycling of the material flow 2, the total yield of chemical products on different catalysts can reach 83 to 85%.

(33) FIG. 4, FIG. 5 and FIG. 6 are diagrams of changes to lower alkenes in the first catalytic reaction products vs. reaction time in Example 8, Example 9 and Example 10, respectively.

(34) Only a few embodiments of the present application are described above, which are not intended to limit the present application in any form. Although the present application is disclosed with the preferred embodiments as above, they are not used to limit the present application. Variations or modifications made by a person skilled in the art by using the above disclosed technical content and without departing from the technical solutions of the present application are equivalent implementation cases and shall be encompassed by the technical solutions.