C-SiC loaded platinum-based catalyst, preparation method and applications thereof

A catalyst, platinum-based technology, applied in the field of platinum-based catalysts, can solve the problems of non-resistance to sintering, low catalyst activity, etc., and achieve the effects of improving conversion rate, simple and feasible preparation method, and avoiding catalyst carbon deposition and deactivation.

Active Publication Date: 2015-11-04

SINOPEC YANGZI PETROCHEM +1

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AI-Extracted Technical Summary

Problems solved by technology

[0005] One of the objectives of the present invention is to provide a C-SiC loaded platinum-...

Method used

[0033] By coordinating the use of the promoter elements, the problems of low activity and fast decay of activity in prior art catalysts can be effectively solved, and thus the finally obtained catalyst shows high catalytic activity and remains stable for a long time. For example, when using the catalyst of the present invention to carry out the dehydrogenation reaction of an alkyl compound to produce the corresponding alkenyl compound, the activity measured at the moment when the reaction is carried out for 1 hour (also referred to as after 1 hour of reaction) (in the form of The conversion rate of paraffini...

Abstract

The present invention discloses a C-SiC composite carrier loaded platinum-based catalyst and a preparation method thereof, and applications of the C-SiC composite carrier loaded platinum-based catalyst in catalytic dehydrogenation reactions of alkyl compounds having more than or equal to a C2-C12 chain. The catalyst comprises, by mass, 96-99.2% of a carrier C-Si, 0.05-2% of a platinum component loaded on the C-SiC, and 0.02-2.0% of an auxiliary agent element loaded on the C-SiC. According to the present invention, the preparation method is simple, feasible and environmentally friendly; compared with the catalyst in the prior art, the C-SiC loaded platinum-based catalyst has the following characteristics that the catalyst integrates the high surface area and the high porosity of the carbon material, the strong interaction between the noble metal Pt and the carbon material, and the like so as to significantly improve the conversion rate of the chain alkyl compound and the selectivity of the corresponding chain alkenyl compound; and the catalyst SiC of the present invention further has excellent thermal conductivity, such that the problems that the local reactor overheating causes the catalyst carbon deposition and deactivation and the like can be avoided.

Application Domain

HydrocarbonsMetal/metal-oxides/metal-hydroxide catalysts +1

Technology Topic

ChemistryPrecious metal +11

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Examples

Experimental program(22)
Comparison scheme(1)

Example Embodiment

[0039] The preparation method of C-SiC supported platinum-based catalyst comprises the following steps:

[0040] (1) The step of contacting the platinum component precursor, the auxiliary element precursor and C-SiC according to a predetermined ratio (preferably in the presence of a dispersion medium such as water) to obtain a contact product (hereinafter referred to as the contact step);

[0041] (2) A step of calcining the contact product to obtain the C-SiC supported platinum-based catalyst (hereinafter referred to as the calcining step).

[0042] The predetermined ratio can be such that the composition of the C-SiC supported platinum-based catalyst finally obtained after the calcination step complies with the foregoing provisions of the present invention.

[0043] The platinum component precursor refers to the substance that can generate the platinum mentioned above through the roasting of the step (2), preferably the soluble salt and soluble acid of platinum, more preferably the water-soluble salt and water-soluble acid of platinum, and further preferably At least one selected from platinum acetate, nitrate, halide salt and halogenated acid, more preferably at least one selected from platinum nitrate, chloride salt and chloride acid. For example, platinum acetate, platinum nitrate, platinum chloride, and chloroplatinic acid.

[0044] These platinum component precursors may be used alone or in combination.

[0045] According to the present invention, the auxiliary element precursor refers to the substance that can generate the auxiliary element mentioned above through the roasting of the step (2), such as the soluble salt of the auxiliary element, and the water-soluble salt of the auxiliary element. Active salt, more preferably at least one selected from the acetate, nitrate and halide salts of the preservative element, more preferably at least one selected from the sulfate, nitrate and chloride salt of the preservative element. For example, tin chloride, stannous sulfate, lithium nitrate, potassium nitrate, lithium acetate, cerium nitrate, potassium acetate, etc. are mentioned.

[0046] These auxiliary element precursors may be used alone or in combination.

[0047] The auxiliary elements are selected from Group A below. Group A: Li, Na, K, Ca, Mg, Mn, W, Zn, Au, Sn, La and Ce.

[0048] In the contacting step, there is no particular limitation on the contact order or contact order of the respective raw material components (ie, the platinum component precursor, the additive element precursor, and the C—SiC). In addition, there is no particular limitation on the manner of performing the contacting step, as long as sufficient contacting of each raw material component can be achieved and a uniform contacting product can be formed. For example, each raw material component can be mixed (assisted stirring if necessary) in any manner known in the art until uniform.

[0049] If necessary, in order to make the contact more uniform and sufficient, or to facilitate the conduct of the contact, the contacting step can also be performed in the presence of a dispersion medium such as water. The contact product obtained at this point may be in the form of a slurry.

[0050] This contacting step can be performed at any temperature from 0°C to 70°C. From the viewpoint of convenience, normal temperature is preferable, but it may not be limited thereto. The contact time is subject to obtaining a uniform contact product, generally 0.5 to 5 hours, sometimes not limited thereto.

[0051] After the root contact product is prepared, especially when the contact product is a slurry, sometimes it can also be dried by any means known in the art (such as at 60-150 ° C, preferably at 70-120 ° C), to remove Any dispersion medium (such as water) that may be introduced during its preparation. According to the invention, the dried contact product is also simply referred to as contact product.

[0052] The platinum component precursor and/or the auxiliary element precursor may be used in the form of a solution. From the viewpoint of ease of handling, the form of an aqueous solution is preferred. At this time, the platinum component precursor and the auxiliary element precursor can be prepared separately into solutions, and then each solution is introduced into the contact step simultaneously or successively, or a mixed solution of the two can be prepared, The mixed solution is then introduced into the contacting step, and is not particularly limited. Simultaneously with this introduction operation, or after the completion of this introduction operation, a pH adjuster and the like can be further introduced according to a method known in the art as needed, and the amount thereof can be conventionally adjusted.

Example Embodiment

[0053] According to one embodiment of the present invention, the contacting step comprises the following steps:

[0054] (1a) Weighing a predetermined amount of platinum component precursor and additive element precursor, mixing and dissolving them in water, optionally adding an appropriate amount of pH regulator etc. as needed, to prepare an aqueous solution;

[0055] (1b) mixing a predetermined amount of C-SiC with the aqueous solution under stirring to obtain a mixed slurry; and

[0056] (1c) drying (such as at 60-150° C., preferably at 70-120° C.) the mixed slurry to obtain the contact product.

[0057] The "predetermined amount" specified here for the platinum component precursor, the auxiliary element precursor and C-SiC meets the requirements of the present invention with the composition of the C-SiC supported platinum-based catalyst finally obtained after the calcination step The foregoing provisions shall prevail, and no special provisions are required. In view of this, those skilled in the art can select an appropriate predetermined amount for each raw material component based on the foregoing provisions, and no particular limitation is required.

[0058] The content of platinum components and auxiliary elements in the obtained C-SiC supported platinum-based catalyst can be determined by general elemental analysis methods, such as ICP (plasma emission spectroscopy) and XRF (X-ray fluorescence spectroscopy).

[0059] The calcining step is carried out at 500-750°C, preferably 580-690°C.

[0060] The application of the C-SiC supported platinum-based catalyst in the catalytic dehydrogenation of C2-C12 alkanyl compounds, and the conversion of C2-C12 alkanyl groups carried by the compounds into corresponding alkenyl groups. As the C2~C12 chain alkyl compound, it can be any compound with one or more C2~C12 chain alkyl groups, such as the organic skeleton with one or more C2~C12 chain alkyl groups ( Such as ethers, hydrocarbons, esters, heterocycles, siloxanes, silanes, polymers, cellulose, etc.) or inorganic frameworks (such as titanic acid (ester), silicic acid (ester), atomic silicon , atomic magnesium, atomic aluminum, etc.), among which C0-C30 hydrocarbons with one or more C2-C12 alkanyl groups are preferred.

[0061] C0-C30 hydrocarbons include, for example, C1-C30 alkanes such as methane, ethane, and propane; C3-C30 cycloalkanes such as cyclopropane, cyclobutane, and cyclohexane; C2-C30 alkenes such as ethylene and propylene; C4-C30 cyclic olefins such as butene and cyclohexene, C2-C30 alkynes such as acetylene and propyne, C6-C30 aromatic hydrocarbons such as benzene, toluene, ethylbenzene, naphthalene, and styrene.

[0062] When the number of carbon atoms in the hydrocarbon is 0, the expression "C0 hydrocarbons with one or more C2-C12 alkanes" refers to C2-C12 alkanes, preferably C2-C6 alkanes, such as ethane , n-propane, isopropane, n-butane, isobutane, sec-butane, n-pentane, isohexane, etc.

[0063] Apparently, one or more C2-C12 alkanyl groups exist in the C2-C12 alkanyl compound as pendant groups pendant on the backbone of the compound.

[0064] The C2-C12 alkyl compound preferably has 1-5 C2-C12 alkyl groups, more preferably 1-3, further preferably 1 or 2. As the C2-C12 alkyl group, for example, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, n-pentyl group, etc., among which C2-C6 chain alkyl group is preferred , more preferably ethyl.

[0065] As C0~C30 hydrocarbons with one or more C2~C12 chain alkyl groups, more preferably C0~C30 hydrocarbons with one ethyl group, such as ethane, propane, isobutane, isopentane, Ethylbenzene, ethylcyclohexene, etc.

[0066] A C2-C12 alkyl compound can be used individually by 1 type as needed, and can also be used in combination of multiple types.

[0067] According to the application, the C-SiC supported platinum-based catalyst is contacted with a C0-C30 hydrocarbon (preferably a mixture of the C2-C12 alkanyl compound and hydrogen) with more than one C2-C12 alkanyl Hydrogen reaction converts C0-C30 hydrocarbons with one or more C2-C12 alkanyl groups into their corresponding alkenyl groups.

[0068] Except for the reaction conditions specified below, the contact reaction can be carried out in any manner known in the art (such as contact method, reaction vessel, catalyst or mixed material feeding method, etc.), which will not be repeated here.

[0069] The conditions of the catalytic dehydrogenation reaction include: the temperature is 550-650°C, preferably 570-610°C, the pressure is 0.1-1.0MPa, preferably 0.1-0.5MPa, and the weight space velocity of the C2-C12 alkyl compound is 1-8h -1 , the molar ratio of C2-C12 alkanyl compound to hydrogen is 1:0.5-1:20.

[0070] According to needs, before the catalytic dehydrogenation reaction, the catalyst needs to be reduced under the condition of hydrogen at 200-400°C for 1-5 hours, and the hydrogen space velocity is 10-50mL/(g cat min).

[0071] According to needs, before contacting with the catalyst, the C2-C12 alkanyl compound or the mixed material can be preheated to 250-600°C, preferably 320-500°C.

[0072] When the C2-C12 chain alkyl compound has only one C2-C12 chain group, the catalytic dehydrogenation reaction of the C2-C12 chain group occurs. When the C2~C12 chain alkyl compound has multiple C2~C12 chain groups, it is hoped that at least one of the C2~C12 chain groups has undergone the catalytic dehydrogenation reaction, but it is not required that all the C2~C12 chain groups All C12 alkanyl groups are capable of undergoing the catalytic dehydrogenation reaction, although it is sometimes desirable according to actual needs.

[0073] In addition, catalytic dehydrogenation generally results in the conversion of a C2-C12 alkenyl group to its corresponding C2-C12 alkenyl group by the removal of two hydrogen atoms. As a result, the resulting C2-C12 alkenyl typically contains only one carbon-carbon double bond, but sometimes it does not. The position of the carbon-carbon double bond on the C2-C12 alkenyl group is also not limited, for example, it may be located at the chain end of the C2-C12 alkenyl group or near the chain end, but it is not limited thereto.

Example Embodiment

[0074] Example 1

[0075] Dissolve 0.017g of platinum nitrate (molecular weight: 319.09) and 0.041g of lithium nitrate (molecular weight: 68.9) in 15ml of water to make a mixed solution of platinum nitrate and lithium nitrate, and add BET to the above solution with a surface area of 125m 2 g -1 20.1g CDC-SiC porous C-SiC sample with an average pore diameter of 12.2nm (prepared with reference to Journal of Materials Chemistry, 2012, Volume 22, pages 14155-14159), stirred in a constant temperature water bath at 80°C for 10 minutes, and dried at 120°C , and calcined at 620°C for 5 hours to obtain a C-SiC supported platinum-based catalyst, code-named A1, in which the mass percentage of Pt was determined to be 0.05%, and the mass percentage of Li was 0.02%. The prepared C-SiC supported platinum-based catalyst was loaded into a fixed-bed reactor, passed through hydrogen for reduction at 200°C for 5 hours, and then passed through a mixture of propane and hydrogen preheated to 340°C (volume ratio of 1: 1), at 0.1MPa, the weight space velocity is 1h -1 And under the condition of reaction temperature 600 ℃, reaction result is shown in table 1.

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