Catalyst for preparing guaiacol from catechol as well as preparation method and application of catalyst

Abstract

The invention provides a catalyst for preparing guaiacol from catechol as well as a preparation method and application of the catalyst. The structural formula of the catalyst is AmBnPOx, A is any one of Mg, Ca and Ba, and B is any one of Y, Ce, La and Pr. The catalyst can reduce the generation amount of the main byproduct veratrole and improve the selectivity on one hand, and can improve the stability of the catalyst, reduce the occurrence of coking and carbon deposition on the other hand, and prolong the service life of the catalyst. In one preferable scheme of the invention, when organophosphate is used as the forming aid, the problem of poor stability caused by volatilization of phosphorus element in the running process of the catalyst can be solved. The catalyst shows high activity, high selectivity and good stability when being applied to the reaction process of preparing guaiacol from catechol; meanwhile, the catalyst is simple in preparation process, easily available in raw materials, low in production cost and easy for industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to a catalyst for preparing guaiacol from catechol, a preparation method and application thereof. Background Art

[0002] Guaiacol, also known as o-hydroxyanisole, o-methoxyphenol, etc., is an important fine chemical intermediate and chemical raw material, widely used in medicine, fragrance, dyes and other fields. The synthesis methods of guaiacol mainly include diazonium salt catalytic oxidation method, liquid phase catalytic synthesis method, phase transfer catalytic synthesis method, gas phase catalytic synthesis method, etc. Among them, the first three methods are all carried out by liquid phase intermittent method. Although the synthesis steps are simple, the post-processing process is cumbersome, and there are problems such as severe corrosion, toxicity, and environmental pollution.

[0003] The most widely used gas-solid catalytic synthesis method is to synthesize o-hydroxyanisole using catechol and methanol as raw materials. The raw materials used in this method are not only less toxic and less corrosive, but also inexpensive, and it is the most promising process route. However, the most important step in this process is the selection of catalysts. The catalysts currently studied generally have the disadvantages of low activity, poor stability, poor selectivity for guaiacol, and many types of by-products.

[0004] In the literature, aluminum phosphate is often used as a catalyst. Liu Gang et al. used the catalyst AlPO (phosphorus aluminum molar ratio = 1) for the gas phase reaction of catechol and methanol to guaiacol, which was highly active, with catechol conversion rate and guaiacol selectivity reaching 70.8% and 70.7%, respectively; Zhu Xuemei et al. investigated the stability of the aluminum phosphate catalyst used for the gas phase reaction of catechol and methanol to guaiacol, and found no significant decrease in catalytic activity within 480 hours. During this period, the catechol conversion rate was >84%, and the guaiacol selectivity was about 90%, showing good reaction performance. Chinese patent CN 103706383A discloses a catalyst for the reaction of catechol to guaiacol, the structural formula of which is AmBnAlxPOy, wherein A is any one of Na, K, Mg or Cs, and B is any one of Co, Ti, Mn, Fe, Ni, Cu or Cr, and the conversion rate can reach 85%, and the selectivity can reach 90%.

[0005] The catalysts mentioned in the above documents and patents are all aluminum phosphate systems. Al itself has a certain strong acidity. Even if it is prepared into aluminum phosphate and alkaline additives such as alkali metals or alkaline earth metals are added, it is difficult to neutralize the strong acid sites on its surface. This strong acid site is the main reason for the coking and carbon deposition of the catalyst. In addition, the binding force between Al and PO4 is not particularly strong, so it is more likely to volatilize phosphorus, resulting in a reduction in P-OH on the catalyst surface. This situation will lead to an increase in the dietherification reaction, that is, an increase in the amount of veratrole in the by-product, and on the other hand, it will also lead to a decrease in catalyst activity and poor stability.

[0006] Therefore, it is necessary to develop a catalyst with fewer strong acidic sites on the surface and less phosphorus volatilization to reduce the production of the main by-product of the reaction, veratrol, and reduce the amount of coking and carbon deposition, while improving the catalyst activity, selectivity and stability. Summary of the invention

[0007] In view of the above problems existing in the prior art, the object of the present invention is to provide a catalyst for preparing guaiacol from catechol, which can reduce the amount of the main by-product veratrol produced and improve the selectivity on the one hand, and improve the stability of the catalyst on the other hand, reduce the occurrence of coking and carbon deposition, and extend the service life of the catalyst.

[0008] Another object of the present invention is to provide a method for preparing the catalyst. In one preferred embodiment, when an organic phosphate is used as a molding aid, the problem of poor stability caused by the volatilization of phosphorus during the operation of the catalyst can be solved.

[0009] Another object of the present invention is to provide use of the catalyst in the preparation of guaiacol.

[0010] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solution:

[0011] The first aspect of the present invention relates to a catalyst for preparing guaiacol from catechol, wherein the structural formula of the catalyst is:

[0012] AmBnPOx,

[0013] Wherein: A is any one of Mg, Ca and Ba;

[0014] B is any one of Y, Ce, La and Pr;

[0015] The value range of m is 0.01~0.10;

[0016] The value range of n is 0.90~1.00;

[0017] The value range of x is 3.9 to 4.1.

[0018] In some preferred examples of the present invention, the catalyst particle size is 3 to 5 mm.

[0019] The second aspect of the present invention relates to a method for preparing a catalyst for preparing guaiacol from catechol, comprising the following steps:

[0020] (1) mixing metal salt A and metal salt B with water, then adding them to an aqueous solution of a phosphorus source, and then adding an alkali solution to adjust the pH value to 7.0 to 8.5 to obtain a slurry;

[0021] (2) filtering, washing, drying and calcining the slurry of step (1) to obtain a catalyst precursor;

[0022] (3) Adding a molding aid to the catalyst precursor in step (2) and mixing them evenly, extruding and molding, and performing secondary calcination to obtain the catalyst.

[0023] In some specific examples of the present invention, the metal salt A in step (1) is selected from a soluble salt of metal A, preferably a nitrate;

[0024] Preferably, the A metal salt includes but is not limited to any one of magnesium nitrate, calcium nitrate and barium nitrate.

[0025] In some specific examples of the present invention, the B metal salt in step (1) is selected from a soluble salt of B metal, preferably a nitrate;

[0026] Preferably, the B metal salt includes but is not limited to any one of yttrium nitrate, cerium nitrate, lanthanum nitrate and praseodymium nitrate.

[0027] In some specific examples of the present invention, the phosphorus source in step (1) is selected from at least one of diammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate and phosphoric acid.

[0028] In some specific examples of the present invention, the molar ratio of the metal salt A to the metal salt B and the phosphorus source in step (1) is (0.01-0.1): (0.9-1): 1, preferably (0.03-0.05): (0.96-0.98): 1, calculated as metal A, metal B and phosphorus element, respectively;

[0029] Preferably, the metal salt A and the metal salt B are mixed with water, and the total concentration of the metal salt A and the metal salt B in the obtained mixed solution is 10-20 wt%;

[0030] Preferably, the concentration of the aqueous solution of the phosphorus source is 10-20 wt %.

[0031] In some specific examples of the present invention, the alkali solution in step (1) is an aqueous solution of an inorganic alkali;

[0032] Preferably, the inorganic base is selected from at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate and aqueous ammonia.

[0033] In some specific examples of the present invention, the molding aid in step (3) is selected from solid phosphate compounds, preferably alkyl phosphate compounds, more preferably at least one of n-dodecyl phosphate, n-tetradecyl phosphate, and n-hexadecyl phosphate, and further preferably n-dodecyl phosphate;

[0034] Preferably, the particle size of the molding aid is distributed between 20 and 200 meshes, preferably between 50 and 150 meshes;

[0035] In some specific examples of the present invention, the amount of the molding aid added in step (3) is 1 to 5% of the mass of the catalyst precursor, preferably 2 to 3%.

[0036] The third aspect of the present invention also relates to the use of the above catalyst in the reaction of preparing guaiacol from catechol.

[0037] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0038] The catalyst for preparing guaiacol from catechol provided by the present invention has excellent activity, selectivity and stability, and its reaction conversion rate is as high as more than 90%, and the selectivity is greater than 98%. In addition, the catalyst of the present invention also has good mechanical strength and use strength, and can well deal with the carbon deposition problem, thereby extending the service life of the catalyst. DETAILED DESCRIPTION

[0039] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0040] A catalyst for preparing guaiacol from catechol, the structural formula of which can be expressed as:

[0041] AmBnPOx,

[0042] Wherein: A is any one of Mg, Ca and Ba;

[0043] B is any one of Y, Ce, La and Pr;

[0044] The value range of m is 0.01 to 0.10, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, etc.;

[0045] The value range of n is 0.90 to 1.00, for example, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, etc.;

[0046] x is the number of oxygen atoms coordinated with other elements, and its value range is 3.9 to 4.1, for example, 3.90, 3.92, 3.94, 3.96, 3.98, 4.00, 4.02, 4.04, 4.06, 4.08, 4.10, etc.

[0047] In the present invention, the catalyst particle size is 3 to 6 mm, for example, 3 mm, 4 mm, 5 mm, 6 mm;

[0048] The shape of the catalyst can be selected according to actual needs, for example, it can be cylindrical, toothed ball, square column, rectangular column and triangular column, etc.; the preferred specifications are 3mm*3mm cylinder, 4mm*4mm cylinder or 5mm*5mm cylinder, preferably 4mm*4mm cylinder.

[0049] The catalyst for preparing guaiacol from catechol of the present invention has no strong acid sites on the surface, can greatly reduce the occurrence of coking and carbon deposition, and prolong the service life of the catalyst. The P element in the catalyst composition can form a P-OH structure on the catalyst surface to provide an acid center for the catalyst, the B element can provide an alkaline center, and the A element is used to adjust the acidity and alkalinity, so that the catalyst surface presents weak acid and weak alkalinity, which is more conducive to improving the selectivity and stability of the catalyst.

[0050] In the catalyst composition of the present invention, the metal element and the phosphorus-containing group (phosphate) have a strong binding force, which can greatly reduce the volatilization of the phosphorus element and maintain a suitable amount of P-OH on the catalyst surface, which can reduce the generation of the main byproduct veratrol on the one hand and improve the stability of the catalyst on the other hand.

[0051] In the present invention, the B element is selected from any one of yttrium, cerium, lanthanum and praseodymium. Compared with aluminum, its phosphate is more insoluble and more stably combined with phosphate. The P element is more difficult to volatilize and has more abundant surface phosphorus hydroxyl groups, so the catalyst has higher selectivity and better stability.

[0052] In the present invention, the catalyst for preparing guaiacol from catechol is prepared by a conventional process well known in the industry, such as an impregnation method, a precipitation method, etc. Generally speaking, any preparation method that can prepare a catalyst having the above-mentioned catalyst structural formula is applicable;

[0053] Specifically, a method for preparing a catalyst for preparing guaiacol from catechol comprises the following steps:

[0054] (1) mixing metal salt A and metal salt B with water, and then adding them to an aqueous solution of a phosphorus source, and then adding an alkali solution to adjust the pH value to 7.0 to 8.5, such as 7.0, 7.2, 7.4, 7.6, 7.8, 8.0, 8.2, 8.4, 8.5, etc., to obtain a slurry;

[0055] (2) filtering, washing, drying and calcining the slurry of step (1) to obtain a catalyst precursor;

[0056] (3) Adding a molding aid to the catalyst precursor in step (2) and mixing them evenly, extruding and molding, and performing secondary calcination to obtain a catalyst.

[0057] Wherein, the metal salt A in step (1) is selected from a soluble salt of metal A, preferably a nitrate;

[0058] Preferably, the A metal salt includes but is not limited to any one of magnesium nitrate, calcium nitrate and barium nitrate.

[0059] Wherein, the B metal salt in step (1) is selected from a soluble salt of B metal, preferably a nitrate;

[0060] Preferably, the B metal salt includes but is not limited to any one of yttrium nitrate, cerium nitrate, lanthanum nitrate and praseodymium nitrate.

[0061] Wherein, the phosphorus source in step (1) is selected from at least one of diammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate and phosphoric acid.

[0062] Wherein, in step (1), the amount of metal salt A, metal salt B and phosphorus source is weighed according to the structural formula of the catalyst AmBnPOx. Specifically, the molar ratio of metal salt A to metal salt B and phosphorus source is (0.01-0.1): (0.9-1): 1, preferably (0.03-0.05): (0.96-0.98): 1, for example (0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1): (0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.00): 1, etc.

[0063] Preferably, the metal salt A and the metal salt B are mixed with water, and the total concentration of the metal salt A and the metal salt B in the obtained mixed solution is 10-20wt%, for example, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, etc.;

[0064] Preferably, the concentration of the aqueous solution of the phosphorus source is 10-20wt%, for example 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt% and the like.

[0065] The method of using alkali solution to adjust the pH value to the target range in step (1) is well known in the art. The alkali solution is usually an aqueous solution of alkali, and is slowly added into the system by dripping under stirring to achieve precise control of the pH value.

[0066] Specifically, the alkali solution is an aqueous solution of an inorganic alkali, and the concentration is 10-20wt%, such as 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, etc.;

[0067] Preferably, the inorganic base is selected from at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate and aqueous ammonia.

[0068] Among them, step (2) filtering, washing, drying and calcining the slurry are some conventional operations used in the preparation process of the solid catalyst and do not need to be specifically limited;

[0069] For example, the purpose of washing operation is to remove soluble salt ions in the filter cake. Generally speaking, when the conductivity of the washing water is tested to be ≤200us / cm, it can be considered that the washing end point has been reached.

[0070] For example, the drying is a conventional drying operation, the drying temperature can be 50-120°C, such as 50°C, 70°C, 90°C, 100°C, 120°C, etc., and the drying time can be more than 6 hours, such as 6.0h, 6.5h, 7.0h, 7.5h, 8.0h, 9.0h, 10.0h, etc.;

[0071] For example, the calcination is a conventional calcination operation. Preferably, the calcination temperature is 450-600°C, for example, 450°C, 500°C, 550°C, 600°C, etc., preferably 500-550°C; the calcination time is 3-8h, preferably 4-6h, for example, 4.0h, 4.5h, 5.0h, 5.5h, 6.0h, etc.

[0072] Wherein, step (3) adopts compression molding method, by adding a certain amount of molding aid (i.e., binder) to the catalyst precursor powder, and after mixing evenly, using external force to compress the powder to form, a catalyst product with stable structure can be obtained. Wherein, the type and amount of the molding aid, unless otherwise specified, can be conventionally selected from the range of existing publicly available molding aids according to the plasticity of the catalyst precursor powder;

[0073] Preferably, the molding aid is selected from solid phosphate compounds, preferably alkyl phosphate compounds, more preferably at least one of n-dodecyl phosphate, n-tetradecyl phosphate, and n-hexadecyl phosphate, and further preferably n-dodecyl phosphate; specific experimental verification has found that when the present invention selects this type of compound as a molding aid, the stability of the catalyst can be further improved.

[0074] Phosphate molding additives are used, which decompose into carbon dioxide, water vapor and free phosphorus during the catalyst roasting stage. The phosphorus element will fill the P vacancy of the catalyst, increase the binding force between phosphorus and B metal, and reduce the volatilization of phosphorus, thereby further improving the selectivity and stability of the catalyst; at the same time, other substances such as carbon dioxide and water vapor evaporate in the form of gas, increasing the development of the catalyst pores, and the generated by-product heavy components can more easily pass through the pores smoothly, further reducing the risk of catalyst coking and carbon deposition.

[0075] Preferably, the particle size of the molding aid is distributed between 20 and 200 meshes, such as 20 mesh, 40 mesh, 60 mesh, 80 mesh, 100 mesh, 120 mesh, 140 mesh, 160 mesh, 180 mesh, 200 mesh, etc., preferably 50 to 150 mesh.

[0076] The amount of the molding aid added in step (3) is 1-5% of the mass of the catalyst main powder precursor, such as 1%, 2%, 3%, 4%, 5%, etc., preferably 2-3%.

[0077] Wherein, the secondary calcination in step (3) is also a conventional calcination operation. Preferably, the calcination temperature is 350-500°C, for example, 350°C, 400°C, 450°C, 500°C, etc., preferably 400-450°C; the calcination time is 3-8h, preferably 4-6h, for example, 4.0h, 4.5h, 5.0h, 5.5h, 6.0h, etc.

[0078] The catalyst provided by the present invention can be used for preparing guaiacol, especially for preparing guaiacol from catechol.

[0079] Based on the existing research, the present invention also defines some specific operating conditions in the reaction of preparing guaiacol from catechol. It should be noted that the following method disclosed in the present invention is only used to illustrate some of the preferred schemes adopted to achieve the purpose of the present invention. In fact, all methods for preparing guaiacol from catechol by using the catalyst should be included in the scope of the technical solution to be protected by the present invention, and are not limited by the following method examples.

[0080] Preferably, a method for preparing guaiacol by gas phase reaction of catechol and methanol comprises the following steps:

[0081] Under nitrogen protection, in a fixed bed reactor filled with the catalyst of the present invention, catechol and methanol are reacted to prepare guaiacol.

[0082] Preferably, the molar ratio of methanol to catechol is 3 to 5:1, for example, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, etc.;

[0083] The reaction pressure is 0.01-0.05 MPa, such as 0.01 MPa, 0.02 MPa, 0.03 MPa, 0.04 MPa, 0.05 MPa, etc., and the temperature is 240-260°C, such as 240°C, 245°C, 250°C, 255°C, 260°C, etc.; the mass space velocity, calculated as catechol, is 0.1-0.2 h -1 , for example 0.10h -1 、0.12h -1 、0.14h -1 、0.16h -1 、0.18h -1 , 0.20h -1 wait.

[0084] Specifically, the method for preparing guaiacol by gas-phase reaction of catechol and methanol comprises the following steps: placing a catalyst in a fixed bed reactor, purging with nitrogen and heating the reactor until the temperature reaches 240-260° C., and stopping the nitrogen flow; using a feed pump to mix catechol and methanol and bring them to a fixed bed reaction tube for reaction, wherein the molar ratio of methanol to catechol is 3-5:1, and the mass space velocity (calculated in terms of catechol) is 0.1-0.2 h -1 The reaction pressure was 0.01-0.05 MPa, and samples were collected from the condenser at the bottom of the reaction tube for analysis every 4 hours or so during the reaction process.

[0085] The method of the present invention is described in detail below in conjunction with embodiments, but is not limited to the embodiments.

[0086] The raw materials and reaction liquid were analyzed by Agilent 7890A gas chromatograph. The detector was a hydrogen flame detector and the chromatographic column was VOC (30m×0.25mm×0.25μm).

[0087] Unless otherwise specified, the chemical raw materials and reagents used in the following examples were purchased from commercial sources and were all analytically pure, and the amounts used did not include crystal water;

[0088] The catalyst specification takes 4mm*4mm cylinder as an example.

[0089] Example 1

[0090] According to Mg 0.05 Y 0.96 PO 3.99 Catalyst A was prepared with a catalyst composition of

[0091] Weigh 263.92 g (0.96 mol) of yttrium nitrate and 5.82 g (0.05 mol) of magnesium nitrate, add deionized water to prepare a metal salt solution with a total concentration of 20 wt%, add the metal salt solution to an aqueous solution with a concentration of 15 wt% and containing 115.03 g (1 mol) of diammonium phosphate, and then adjust the pH value to 7.5 with a 10 wt% aqueous sodium carbonate solution to obtain a mixed slurry.

[0092] The slurry was filtered, washed, and dried at 120° C. for 6 h, and then calcined at 550° C. for 4 h to obtain a catalyst precursor.

[0093] 3% by weight of n-dodecyl phosphate (particle size distribution 20-200 mesh) was added to the catalyst precursor and mixed evenly, and tabletted. The catalyst precursor was then calcined for a second time at 400° C. for 6 h to obtain a final catalyst product A.

[0094] Example 2

[0095] According to Ca 0.05 Ce 0.96 PO 3.99 Catalyst B was prepared using a catalyst composition of .

[0096] 313.08 g (0.96 mol) of cerium nitrate and 8.2 g (0.05 mol) of calcium nitrate were weighed and deionized water was added to prepare a metal salt solution with a total concentration of 10 wt%. The metal salt solution was added to an aqueous solution with a concentration of 15 wt% and containing 132.06 g (1 mol) of diammonium hydrogen phosphate, and the pH value was adjusted to 8 with a 15 wt% aqueous sodium carbonate solution to obtain a mixed slurry.

[0097] The slurry was filtered, washed, and dried at 120° C. for 6 h, and then calcined at 500° C. for 6 h to obtain a catalyst precursor.

[0098] 3% by weight of n-tetradecyl phosphate (particle size distribution 20-200 mesh) was added to the catalyst precursor, mixed evenly, pressed into tablets, and calcined at 450° C. for 4 hours to obtain the final catalyst product B.

[0099] Example 3

[0100] According to Ba 0.05 Y 1.00 PO 4.05 Catalyst C was prepared with a catalyst composition of

[0101] 324.92 g (1 mol) of lanthanum nitrate and 13.07 g (0.05 mol) of barium nitrate were weighed and deionized water was added to prepare a metal salt solution with a total concentration of 15 wt%. The metal salt solution was added to an aqueous solution with a concentration of 10 wt% and containing 149.09 g (1.13 mol) of ammonium hydrogen phosphate, and the pH value was adjusted to 8.5 with a sodium carbonate aqueous solution with a concentration of 20 wt% to obtain a mixed slurry.

[0102] The slurry was filtered, washed, and dried at 120° C. for 6 h, and then calcined at 450° C. for 8 h to obtain a catalyst precursor.

[0103] 2% by weight of n-dodecyl phosphate (particle size distribution 0-200 mesh) was added to the catalyst precursor, mixed evenly, pressed into tablets, and calcined at 350° C. for 8 h to obtain the final catalyst product C.

[0104] Example 4

[0105] According to Mg 0.1 Pr 0.90 PO 3.95 Catalyst D was prepared using a catalyst composition of.

[0106] 294.22 g (0.9 mol) of praseodymium nitrate and 11.63 g (0.1 mol) of magnesium nitrate were weighed and deionized water was added to prepare a metal salt solution with a total concentration of 15 wt%. The metal salt solution was added to a 15 wt% aqueous solution containing 98 g (1 mol) of phosphoric acid, and the pH value was adjusted to 7.0 with a 15 wt% aqueous sodium bicarbonate solution to obtain a mixed slurry.

[0107] The slurry was filtered, washed, and dried at 120° C. for 6 h, and then calcined at 600° C. for 3 h to obtain a catalyst precursor.

[0108] 5% by weight of n-dodecyl phosphate (particle size distribution 20-200 mesh) was added to the catalyst precursor, mixed evenly, pressed into tablets, and calcined at 500° C. for 3 h to obtain the final catalyst product D.

[0109] Example 5

[0110] According to Ca 0.01 Y 1.00 PO 4.01 Catalyst E was prepared using a catalyst composition of.

[0111] Weigh 274.92 g (1 mol) of yttrium nitrate and 1.64 g (0.01 mol) of calcium nitrate, add deionized water to prepare a metal salt solution with a total concentration of 15 wt%, add the metal salt solution to a 20 wt% aqueous solution containing 149.09 g (1 mol) of ammonium phosphate, and adjust the pH value to 7.2 with 15 wt% ammonia water to obtain a mixed slurry.

[0112] The slurry was filtered, washed, and dried at 120° C. for 6 h, and then calcined at 550° C. for 4 h to obtain a catalyst precursor.

[0113] 1% by weight of n-dodecyl phosphate (particle size distribution 20-200 mesh) was added to the catalyst precursor, mixed evenly, pressed into tablets, and calcined at 400° C. for 6 h to obtain the final catalyst product E.

[0114] Example 6

[0115] According to Ca 0.03 Ce 0.98 PO 4.00 Catalyst F was prepared using a catalyst composition of

[0116] 319.61 g (0.98 mol) of cerium nitrate and 4.92 g (0.03 mol) of calcium nitrate were weighed, and deionized water was added to prepare a metal salt solution with a total concentration of 20 wt%. The metal salt solution was added to an aqueous solution containing 132.06 g (1 mol) of diammonium hydrogen phosphate at a concentration of 20 wt%, and the pH value was adjusted to 7.8 with a sodium carbonate aqueous solution at a concentration of 20 wt% to obtain a mixed slurry.

[0117] The slurry was filtered, washed, and dried at 120° C. for 6 h, and then calcined at 550° C. for 4 h to obtain a catalyst precursor.

[0118] 4% by weight of n-dodecyl phosphate (particle size distribution 20-200 mesh) was added to the catalyst precursor, mixed evenly, pressed into tablets, and calcined at 450° C. for 4 hours to obtain the final catalyst product F.

[0119] Example 7

[0120] Catalyst G was prepared according to the raw material ratio and method of Example 1, except that n-dodecyl phosphate was replaced with an equal amount of cyclohexane hexol phosphate (particle size distribution 20-200 mesh) during molding, and the other conditions remained unchanged to obtain a finished catalyst G.

[0121] Example 8

[0122] Catalyst H was prepared according to the raw material ratio and method of Example 1, except that n-dodecyl phosphate was replaced with an equal amount of n-hexadecyl phosphate (particle size distribution 20-200 mesh) during molding, and the other conditions remained unchanged to obtain a finished catalyst H

[0123] Comparative Example 1

[0124] Catalyst I (composition: Na 0.05 Al 0.95 PO 3.95 ).

[0125] Comparative Example 2

[0126] According to Mg 1.01 PO 3.99 Catalyst J was prepared with the catalyst composition.

[0127] The preparation method is as described in Example 1, and the type and amount of raw materials added are adjusted according to the structural formula ratio.

[0128] Comparative Example 3

[0129] Follow Y 1.01 PO 3.99 Catalyst K was prepared using a catalyst composition of

[0130] The preparation method is as described in Example 1, and the type and amount of raw materials added are adjusted according to the structural formula ratio.

[0131] Comparative Example 4

[0132] According to Na 0.05 Y 0.96 PO 3.99 Catalyst L was prepared with a catalyst composition of.

[0133] The preparation method is as described in Example 1, and the type and amount of raw materials added are adjusted according to the structural formula ratio.

[0134] Comparative Example 5

[0135] According to Mg 0.05 Al 0.96 PO 3.99 Catalyst M was prepared using a catalyst composition of.

[0136] The preparation method is as described in Example 1, and the type and amount of raw materials added are adjusted according to the structural formula ratio.

[0137] Example 9

[0138] Catalyst evaluation: Catalysts AH prepared in Examples 1-8 and catalysts IM prepared in Comparative Examples 1-6 were used in the gas phase reaction of catechol and methanol to prepare guaiacol.

[0139] The reaction conditions are as follows: 150 ml of catalyst is loaded into a fixed bed reactor with an inner diameter of 26 mm, the reaction temperature is 250°C, the reaction pressure (gauge pressure) is 0.03 MPa, the alcohol / phenol molar ratio is 3:1, and the mass space velocity (calculated as catechol) is 0.15 h -1 Under these conditions, the reaction was carried out to obtain a reaction solution, the reaction solution was analyzed, and the results were calculated. The reaction results are shown in Table 1.

[0140] Table 1 Catalyst evaluation results

[0141]

[0142]

[0143] Note: Conversion rate in the table = (1-the number of moles of catechol remaining in the reaction solution / the number of moles of catechol contained in the raw material) * 100%; selectivity = the number of moles of guaiacol generated / the number of moles of converted catechol * 100%.

[0144] The carbon deposit amount of the catalyst after 480 hours of reaction was detected ("EA" carbon element analyzer multi-EA5100), and the data in Table 2 were obtained.

[0145] Table 2 Carbon deposition of catalyst after reaction

[0146] catalyst Carbon deposit amount after reaction / % A 0.5 B 0.62 C 0.73 D 0.90 E 0.81 F 0.65 G 0.55 H 0.62 I 10.78 J 4.23 K 3.25 L 2.23 M 9.64

[0147] It can be seen from Tables 1 and 2 above that the catalyst prepared by the method of the present invention is used to catalyze the gas phase reaction of catechol and methanol to prepare guaiacol catechol, and has good activity and selectivity, and has good resistance to carbon deposition, thereby ensuring the stability of the catalyst.

Claims

1. A catalyst for preparing guaiacol from catechol, characterized in that: The structural formula of the catalyst is: AmBnPOx, Wherein: A is any one of Mg, Ca and Ba; B is any one of Y, Ce, La and Pr; The value range of m is 0.01~0.10; The value range of n is 0.90~1.00; The value range of x is 3.9 to 4.

1.

2. A method for preparing a catalyst for preparing guaiacol from catechol according to claim 1, characterized in that: The following steps are involved: (1) mixing metal salt A and metal salt B with water, then adding them to an aqueous solution of a phosphorus source, and then adding an alkali solution to adjust the pH value to 7.0 to 8.5 to obtain a slurry; (2) filtering, washing, drying and calcining the slurry of step (1) to obtain a catalyst precursor; (3) Adding a molding aid to the catalyst precursor in step (2) and mixing them evenly, extruding and molding, and performing secondary calcination to obtain the catalyst.

3. The preparation method according to claim 2, characterized in that: The metal salt A in step (1) is selected from a soluble salt of metal A, preferably a nitrate; Preferably, the A metal salt is selected from any one of magnesium nitrate, calcium nitrate and barium nitrate.

4. The preparation method according to claim 2, characterized in that: The B metal salt in step (1) is selected from a soluble salt of B metal, preferably a nitrate; Preferably, the B metal salt is selected from any one of yttrium nitrate, cerium nitrate, lanthanum nitrate and praseodymium nitrate.

5. The preparation method according to claim 2, characterized in that: The phosphorus source in step (1) is at least one selected from diammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium phosphate and phosphoric acid. Preferably, the concentration of the aqueous solution of the phosphorus source is 10-20 wt%.

6. The preparation method according to claim 2, characterized in that: In step (1), the metal salt A, the metal salt B and the phosphorus source are respectively present in a molar ratio of (0.01-0.1):(0.9-1):1, preferably (0.03-0.05):(0.96-0.98):1, based on the metal A, metal B and phosphorus element. Preferably, the metal salt A and the metal salt B are mixed with water, and the total concentration of the metal salt A and the metal salt B in the obtained mixed solution is 10-20 wt %.

7. The preparation method according to claim 2, characterized in that: The alkali solution in step (1) is an aqueous solution of an inorganic alkali; Preferably, the inorganic base is selected from at least one of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate and aqueous ammonia.

8. The preparation method according to claim 2, characterized in that: The molding aid in step (3) is selected from solid phosphate compounds, preferably alkyl phosphate compounds, more preferably at least one of n-dodecyl phosphate, n-tetradecyl phosphate, and n-hexadecyl phosphate, and further preferably n-dodecyl phosphate; Preferably, the particle size of the molding aid is distributed between 20 and 200 meshes, preferably between 50 and 150 meshes.

9. The preparation method according to claim 2, characterized in that: The amount of the molding aid added in step (3) is 1-5% of the mass of the catalyst precursor, preferably 2-3%.

10. Use of the catalyst for preparing guaiacol from catechol according to claim 1 or the catalyst for preparing guaiacol from catechol prepared by the method according to any one of claims 2 to 9.

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