PROCESS FOR FLUID CATALYTIC CRACKING OF A LIGHT TIGHT OIL IN CO-TREATMENT WITH A CONVENTIONAL FCC FEEDSTOCK

Abstract

The present invention relates to a process for fluid catalytic cracking of a feedstock comprising a light tight oil and at least one conventional feedstock in order to produce an effluent, in which the feedstock has a content of light tight oil so that the density of the feedstock is between 0.84 and 0.91.

Claims

1. Process for fluid catalytic cracking of a feedstock comprising a light tight oil and at least one conventional feedstock in order to produce an effluent, in which the feedstock has a content of light tight oil so that the density of the feedstock is between 0.84 and 0.91.

2. Process according to claim 1, in which the conventional feedstock comprises an oil selected from the group consisting of a vacuum gas oil, an atmospheric residue, a coker gas oil, a vacuum residue and a recycle stream from a hydrocracking step.

3. Process according to claim 1, in which the feedstock has a content of light tight oil so that the density of the feedstock is between 0.860 and 0.892.

4. Process according to claim 1, in which the feedstock has a content of light tight oil so that the density of the feedstock is between 0.866 and 0.886.

5. Process according to claim 1, in which the light tight oil comprises at least one of the following features: density between 0.65 and 0.9; C5-220 C. content of greater than 15% by weight and preferably greater than 20% by weight; sulfur content of less than 0.5% by weight; metal content between 0 and 500 ppm.

6. Process according to claim 1, in which the light tight oil comprises at least 30% by weight of compounds having a boiling point below 300 C.

7. Process according to claim 1, in which the light tight oil comprises at least 50% by weight of compounds having a boiling point below 300 C.

8. Process according to claim 1, in which the operating conditions of the process are the following: reactor outlet temperature: between 500 C. and 700 C.; C/O ratio between 2 and 20.

9. Process according to claim 1, using at least one catalytic cracking catalyst comprising a matrix of alumina, of silica or of silica-alumina with a zeolite.

10. Process according to claim 9, in which the catalyst comprises at least 15% by weight of Y zeolite.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 represents a graph showing the change in the gasoline yield as a function of the content of light tight oil in the FCC feedstock (mixture with HDT VGO or ATR).

[0025] FIG. 2 represents a graph showing an optimum RON when the light tight oil content of the FCC feedstock is increased.

[0026] FIG. 3 represents the octane-barrel of the gasoline as a function of the light tight oil content of an FCC feedstock comprising hydrotreated vacuum gas oil.

[0027] FIG. 4 represents the octane-barrel of the gasoline as a function of the light tight oil content of an FCC feedstock comprising atmospheric residue.

[0028] FIG. 5 represents a graph showing that, although the conventional feedstock, the catalyst and the C/O used are modified, the octane-barrel may be increased as a function of the density resulting from the addition of the light tight oil in the FCC feedstock.

DESCRIPTION OF THE EMBODIMENTS

[0029] The invention relates to an FCC process for an FCC feedstock comprising a light tight oil in co-treatment with a conventional FCC feedstock for the production of gasoline having a high yield and high octane number.

[0030] Specifically, it has been found that a feedstock of light tight oil type, for example an unfractionated and/or non-hydrotreated light tight oil (i.e., crude LTO), may be sent to an FCC process in co-treatment with a conventional FCC feedstock (e.g. VGO, ATR, VR, etc.), which is optionally hydrotreated, in order to produce gasoline having a high yield and high octane number.

[0031] The FCC process according to the invention may be defined as comprising the fluid catalytic cracking of an FCC feedstock comprising a light tight oil and at least one conventional feedstock in order to produce an effluent, the FCC feedstock having a content of light tight oil so that the density of the FCC feedstock is between 0.84 and 0.91, preferably between 0.860 and 0.892, very preferably between 0.866 and 0.886. The conventional feedstock may comprise at least one oil selected from the group consisting of a vacuum gas oil, an atmospheric residue, a coker gas oil (CGO), a vacuum residue and a recycle stream from a hydrocracking step.

[0032] According to one or more embodiments, the FCC process comprises the separation and the fractionation of the effluent in order to produce gasoline and optionally dry gas, LPG, LCO and/or a bottoms fraction.

[0033] According to one or more embodiments, the light tight oil comprises at least one of the following features:

[0034] density between 0.65 and 0.9, preferably between 0.7 and 0.9, very preferably between 0.70 and 0.85;

[0035] C5-220 C. content of greater than 15% by weight and preferably greater than 20% by weight relative to the total weight of the light tight oil;

[0036] sulfur content of less than 0.5% by weight relative to the total weight of the light tight oil;

[0037] metal (notably calcium, potassium, iron, etc.) content between 0 and 500 ppm relative to the total weight of the light tight oil.

[0038] According to one or more embodiments, the light tight oil comprises at least 30% by weight of compounds having a boiling point below 300 C., preferably at least 50% by weight relative to the total weight of the light tight oil.

[0039] It is understood in the present description that a product of an FCC process, such as an effluent of an FCC reactor, is not considered to be a conventional FCC feedstock.

[0040] According to one or more embodiments, the operating conditions of the FCC process are the following:

[0041] reactor outlet temperature (ROT): between 500 C. and 700 C., preferably between 500 C. and 600 C.;

[0042] C/O ratio (Catalyst to Oil ratio) between 2 and 20, preferably between 3 and 10.

[0043] According to one or more embodiments, the FCC process uses a catalyst comprising a matrix of alumina, of silica or of silica-alumina with a zeolite. The FCC catalyst may comprise at least 15% by weight of Y zeolite and optionally of ZSM-5 zeolite or other zeolite relative to the total weight of the catalyst.

[0044] The densities are measured by analysis with reference to NF EN ISO 12185, for example in the IFPEN (R05) petroleum analysis laboratory. For the mixtures, the densities are calculated from the densities of the pure feedstocks and as a function of the proportions of the mixture, such as for example: density of Fi+Fj mixture=1/(Fi %/Fi density+Fj %/Fj density) with Fj %=1Fi %.

[0045] The invention will be better understood from reading the following examples.

[0046] Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

[0047] In the foregoing and in the examples, all temperatures are set forth uncorrected in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.

[0048] The entire disclosures of all applications, patents and publications, cited herein and of corresponding French application No. 18/71.365, filed Nov. 5, 2018, are incorporated by reference herein.

EXAMPLES

[0049] Pilot tests were carried out on a small pilot plant (short-contact-time resid test or SCT-RT unit) in order to study the impact of the LTO content on the yields of the products at the outlet. The operating conditions applied for these tests are summarized in Table 1 below:

TABLE-US-00001 Pressure (MPaA) 0.15 Operating mode Adiabatic C/O 4-9 Feedstock injection temperature ( C.) 610 Reactor head temperature ( C.) 530 Weight of feedstock injected (g) 3

[0050] These operating conditions are specific to an SCT-RT unit and are equivalent to operating conditions of a standard FCC unit for a conversion of between 70% and 80% by weight. The conversion being defined according to the following formula: 100(wt % LCO+wt % of the 360 C..sup.+ fraction (i.e., LCO %+SLURRY %)). By way of example, the feedstock injection temperature of 610 C., used as parameter in SCT-RT, would correspond to an ROT in a standard FCC unit of between 500 C. and 590 C.

[0051] The properties of the light tight oil are described in Table 2 below.

TABLE-US-00002 Properties LTO Density @ 15 C. 0.7543 Sulfur (% by weight) 0.07 Conradson carbon (% by weight) 0.5 Total nitrogen (ppm by weight) 306 Basic nitrogen (ppm by weight) 111.9 Ni (ppm by weight) <2 V (ppm by weight) <2 Carbon (% by weight) 85.38 Hydrogen (% by weight) 14.62 Aromatic carbon (%) 9.09 Paraffinic carbon (%) 74.08 Naphthenic carbon (%) 16.83

[0052] This light tight oil was mixed with hydrotreated vacuum gas oil and atmospheric residue, the properties of which are described in Table 3 below.

TABLE-US-00003 Properties HDT VGO ATR Density @ 15 C. 0.9018 0.9387 Sulfur (% by weight) 0.0612 0.5043 Conradson carbon (% by weight) <0.1 4.92 Total nitrogen (ppm by weight) 842 2125 Basic nitrogen (ppm by weight) 192 664.25 Viscosity @ 100 C. (cSt) 7.45 23.08 Viscosity @ 70 C. (cSt) 16.92 70.86 Ni (ppm by weight) <2 4.3 V (ppm by weight) <2 7.6 C5 asphaltenes (% by weight) 0.35 C7 asphaltenes (% by weight) 1.2 Refractive index @ 70 C. 1.4805 1.5005 Carbon (% by weight) 86.85 87.2 Hydrogen (% by weight) 12.79 12.11 Aromatic carbon (% by weight) 15.2 19.5 Paraffinic carbon (% by weight) 60.15 53.7 Naphthenic carbon (% by weight) 24.65 26.8 SAR saturate (% by weight) 52.4 SAR aromatic (% by weight) 40.7 SAR resins (% by weight) 6.9

[0053] The tests were carried out with light tight oil contents ranging from 0 to 100% by weight, a C/O ratio of 4 and a different catalyst for each conventional feedstock, the main properties of which are summarized in Table 4 below.

TABLE-US-00004 Properties Catalyst 1 Catalyst 2 TSA (m.sup.2/g) 345 380 ZSA/MSA 2.45 1.9 REO (% by weight) 0.9 2 ZSM-5 (% by weight) 0 0 TSA: total surface area ZSA: zeolite surface area MSA: matrix surface areas REO: Rare-earth oxide

[0054] In FIGS. 1 to 4, the lozenges represent the results obtained with an FCC feedstock comprising light tight oil and hydrotreated vacuum gas oil in the presence of the catalyst 2 and with a C/O of 4; the triangles represent the results obtained with an FCC feedstock comprising light tight oil and atmospheric residue in the presence of the catalyst 1 and with a C/O of 4).

[0055] FIG. 1 represents a graph showing the change in the gasoline yield as a function of the light tight oil content in the feedstock. The gasoline yield increases with the light tight oil content since the naphtha fraction of the light tight oil is basically greater than that of a conventional FCC feedstock.

[0056] In these examples, the naphtha fraction of the light tight oil is paraffinic (see Table 2) and therefore has, by default, a rather low RON. As explained above, the increase in the gasoline yield comes partly from the naphtha fraction of the light tight oil which is not cracked or not very cracked, it could therefore be expected to have an RON that decreases with the light tight oil content of the mixture. On the contrary, it can be seen in FIG. 2 that there is an optimum RON when the light tight oil content of the mixture is increased, which lies between 10% and 25% in the case of the hydrotreated vacuum gas oil and around 10% in the case of the atmospheric residue.

[0057] In order to increase the production of gasoline, it is possible to make a compromise between the yield obtained and the quality thereof (represented for the most part by its RON/MON). The term MON stands for motor octane number. This compromise may be expressed as octane-barrel (octane-barrel=gasoline yield (BPSD)(RON+MON)/2). The term BPSD stands for barrels per stream day. FIGS. 3 and 4 represent the octane-barrel of the gasoline as a function of the light tight oil content of a feedstock comprising hydrotreated vacuum gas oil and atmospheric residue, respectively. In these examples, the optimum lies at around 15% by weight of light tight oil in the mixture for the hydrotreated vacuum gas oil and closer to 50% by weight of light tight oil in the mixture for the atmospheric residue.

[0058] As shown in FIG. 5, it is possible to increase the octane-barrel by using an FCC feedstock having a content of light tight oil so that the density of the FCC feedstock is between 0.84 and 0.91, preferably between 0.860 and 0.892, very preferably between 0.866 and 0.886. Example A corresponds to an FCC process for a feedstock comprising hydrotreated vacuum gas oil and light tight oil with a C/O of 4 and the catalyst 1. Example B corresponds to an FCC process for a feedstock comprising hydrotreated vacuum gas oil and light tight oil with a C/O of 9 and the catalyst 1. Example C corresponds to an FCC process for a feedstock comprising atmospheric residue and light tight oil with a C/O of 4 and the catalyst 2. FIG. 5 clearly shows that, although the conventional feedstock, the catalyst and the C/O used are modified, the octane-barrel may be increased as a function of the density resulting from the mixing of the light tight oil with the conventional feedstock.

[0059] The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

[0060] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.