Fluid Catalytic Cracking Patents (II): Zeolites – 2012-2013
This is the second article in an ongoing review of recent patent trends in the area of Fluid Catalytic Cracking (FCC). In the last installment, we reviewed patents on catalyst additives and demonstrated that relatively few patents had recently issued on FCC additives (e.g., gasoline sulfur reduction catalysts), likely reflecting the current use of gas oil hydrotreaters and naphtha hydrotreaters/desuphurizers, which reduce the need for such additives. The current article covers recent patents relating to zeolites. Review of these patents indicates that the most active area of research regarding zeolites, at least from the standpoint of companies obtaining patent protection, is in the area of zeolite mesoporosity (zeolite pore diameters in the range of 2 to 50 nm).
The eight zeolite-related patents reviewed can generally be placed into two groups. Four of the patents: U.S. Patent Nos. 8,157,985, 8,247,631, 8,513,150, and 8,617,513 describe zeolite structure or characteristics. The remaining patents, U.S. Patent Nos. 8,361,434, 8,450,232, 8,486,369, and 8,524,624, describe methods of preparing zeolites. Five of the eight patents relate to zeolite mesoporosity. The other three relate to zeolites for enhancing a particular aspect of FCC product yields, e.g., propylene selectivity or alkylation/transalkylation.
The emphasis on zeolite mesoporosity seems to result from the fact that various synthesis techniques for zeolites which affect mesoporosity have been developed by researchers, and there is a market for the positive yield effects that result from the presence of zeolite mesoporosity. It is well known that conventional FCC catalysts consist of a Y zeolite held together by an amorphous silica/alumina “matrix.” The zeolite is relatively stable at the typical operating temperatures of regenerators (up to 1400° F), and is very well suited to selectively crack hydrocarbon chains small enough to enter its 0.7 nm pore diameter, into molecules boiling in the diesel or gasoline range. However, molecules larger than the 0.7 nm threshold present problems for the zeolite. In contrast, while matrix cracking is not as coke selective as zeolite cracking, the matrix is not constrained by the zeolite’s pore size limitations, and can crack large molecules that the zeolite cannot. A portion of the (smaller chain) products obtained from matrix cracking can subsequently enter the pores of the zeolite for further coke selective cracking. In this way, a properly designed FCC catalyst can use the synergy of combinations of zeolite and matrix to provide FCC conversion levels better than the sum of those obtainable by the zeolite and matrix alone.
With regard to the presence of mesoporosity in the zeolite, it appears to function somewhat analogously to the dynamic between zeolite and matrix, so that large molecules are pre-cracked in the mesopores, the products of which can be further cracked in the normal zeolite pores. Thus, while applications requiring significant bottoms-upgrading still require the necessary level and type of matrix component, the presence of mesoporosity would be appropriate with certain feedstocks where incremental coke selective bottoms upgrading is desired along with the conversion/selectivity benefits that accompany it. Presumably, this dynamic continues to drive R&D efforts to design and patent FCC zeolites having mesoporosity, and their methods of manufacture. The ability to incorporate zeolite mesoporosity provides refiners with an additional tool in designing cracking catalysts that best meet their unit’s particular requirements.
Keep an eye out for the next installment in this series, where I will review recent FCC patents in the area of cracking catalysts.
The patents related to zeolites are summarized below. Tables 1 and 2 list relevant information for each patent. Table 3 contains a representative independent claim from each.
U.S. Patent No. 8,157,985, assigned to UOP LLC, generally relates to a process for catalytic cracking using a UZM-35HS zeolite-containing catalyst. The zeolite has an empirical formula of: M1an+Al(1-x)ExSiy’Oz’ where M1 is at least one exchangeable cation selected from the group consisting of alkali, alkaline earth metals, rare earth metals, ammonium ion, hydrogen ion and mixtures thereof, “a” is the mole ratio of M1 to (Al+E) and varies from about 0.05 to about 50, “n” is the weighted average valence of M1 and has a value of about +1 to about +3, E is an element selected from the group consisting of gallium, iron, boron, and mixtures thereof, “x” is the mole fraction of E and varies from 0 to 1.0, y’ is the mole ratio of Si to (Al+E) and varies from greater than about 4 to virtually pure silica and z’ is the mole ratio of O to (Al+E) and has a value determined by the equation: z’=(a●n+3+4y’)/2. In its x-ray diffraction pattern, the zeolite has specified d-spacings and intensities set forth in the claim. The patent is a continuation-in-part of granted patent U.S. Patent No. 7,981,273. The patent contains two independent claims (1 and 14). Claim 1 is summarized in Table 3.
U.S. Patent No. 8,247,631, assigned to UOP LLC, generally relates to a method for catalytic cracking using a UZM-35 microporous crystalline zeolitic composition comprising an MSE type zeolite, an MFI type zeolite, and an ERI type zeolite, where the UZM-35 composition has an empirical formula of: Mm+RrAl1-xExSiy’Oz’ where M represents a combination of potassium and sodium exchangeable cations, “m” is the mole ratio of M to (Al+E) and varies from about 0.05 to about 3, R is a singly charged dimethyldipropylammonium cation, “r” is the mole ratio of R to (Al+E) and has a value of about 0.25 to about 2.0, E is an element selected from the group consisting of gallium, iron, boron and mixtures thereof, “x” is the mole fraction of E and has a value from 0 to about 1.0, “y” is the mole ratio of Si to (Al+E) and varies from greater than 2 to about 12 and “z” is the mole ratio of O to (Al+E) and has a value determined by the equation: z=(m+r+3+4y)/2. In its x-ray diffraction pattern, the zeolite has specified d-spacings and intensities set forth in the claim. The patent contains two independent claims (1 and 15). Claim 1 is summarized in Table 3.
U.S. Patent No. 8,513,150, assigned to ExxonMobil Research and Engineering Company, generally relates to a Y zeolite having a Large Mesopore (pore diameter of greater than 50 to 500 Å) Volume of at least about 0.03 cm3/g, and a Small Mesopore (pore diameter of 30 to 50 Å) Peak of less than about 0.15 cm3/g. The patent is a divisional of U.S. Patent No. 8,361,434 and contains a single independent claim, which is summarized in Table 3.
U.S. Patent No. 8,617,513, assigned to the Massachusetts Institute of Technology, generally relates to a mesostructured crystalline inorganic one-phase hybrid single crystal material having long-range crystallinity. The crystalline inorganic material can be can be selected from zeolites, zeolite-related materials, zeotypes, metal oxides, molecular sieves, and combinations thereof. The patent is a divisional of U.S. Patent No. 7,589,041, and contains four independent claims (1, 22, 28, and 29). Claim 1 is listed in Table 3.
U.S. Patent No. 8,361,434, assigned to ExxonMobil Research and Engineering Company, generally relates to methods for making a Y zeolite having particular Large Mesopore/Small Mesopore volumes (the sieve described in U.S. 8,513,150 above). The method describes ammonium exchange of a zeolite precursor to a particular Na2O content followed by a steam calcination of 1200° F to 1500° F, where the temperature of the zeolite precursor is within 50° F of the steam calcination in less than 5 minutes. The patent contains a single independent claim which is listed in Table 3.
U.S. Patent No. 8,450,232, assigned to Lummus Technology Inc., generally relates to a method for improving the activity of acidic zeolitic catalysts through selective dealumination. The catalysts can be used for the alkylation or transalkylation of aromatic compounds, the alkylation of isoparaffins or in FCC processes. The patent contains a single independent claim which is listed in Table 3.
U.S. Patent No. 8,486,369, assigned to Rive Technology, Inc., generally relates to a method for forming a mesoporous zeolite by first acid washing a non-mesoporous initial zeolite with an acidic medium, where the initial zeolite has a total silicon-to-aluminum ratio of less than 30. The acid-washed zeolite is then contacted with a mesopore-forming medium different than the acidic medium, e.g., contacting the acid-washed zeolite with a pH controlling medium in the presence of a pore forming agent under various time and temperature conditions. The patent contains four independent claims (1, 26, 36, and 47). Claim 1 is listed in Table 3.
U.S. Patent No. 8,524,624, assigned to the Massachusetts Institute of Technology, generally relates to a method for making a mesostructure comprising exposing an inorganic material having long-range crystallinity to a pH controlled medium at a first set of time/temperature conditions, exposing the inorganic material to a surfactant for a second set of time/temperature conditions and then adjusting one or both set of time/temperature conditions to produce a single-phase mesostructured zeolite having a plurality of mesopores and long range crystallinity. By “long range crystallinity” the patent refers to the long-range regular lattice structure of the crystalline state (i.e., the aggregated zeolite nuclei are fully crystalline or truly crystalline. The patent is a divisional of U.S. Patent No. 8,008,223. The patent contains three independent claims (1, 17 and 34). Claim 1 is listed in Table 3.
Click here to view Table 1.
Click here to view Table 2.
Click here to view Table 3.