Pre-activation method of supported metal catalyst, catalyst and application thereof

Abstract

The present invention relates to a preactivation method of a supported metal catalyst for catalyzing the hydrogenolysis reaction of polyols. The catalyst is composed of a carrier and active components A and B, wherein the carrier is one of aluminum oxide, silicon oxide, zirconium oxide, titanium oxide or molecular sieve, the active component A is one of tungsten oxide, molybdenum oxide and niobium oxide, and the active component B is one of precious metals ruthenium, rhodium, palladium, iridium and platinum. The present invention adopts a technical solution that uses pure hydrogen or a mixed gas containing hydrogen and an inert gas, and liquid water as a reducing agent, and the preactivation temperature is 80 to 500° C., and the hydrogen dissolved in the liquid contacts the catalyst, and the high-valent metal oxide in the catalyst is slowly reduced to a low-valent active metal oxide or a metal element, thereby effectively solving the sintering problem of the catalyst in the hydrogen reduction process, thereby significantly improving the reaction activity of the hydrogenolysis of polyols and the selectivity of the target product.

Description

Technical Field

[0001] The present invention relates to a pre-activation method for a supported metal catalyst for polyol hydrogenolysis, which is mainly used for polyol hydrogenolysis reaction. Technical Background

[0002] Lower carbon diols are important polyester monomers, such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, etc. At the same time, they are also widely used in various aspects of the chemical industry as solvents, antifreeze agents, humectants, organic pharmaceutical intermediates, etc. In particular, polytrimethylene terephthalate (PTT) synthesized from 1,3-propanediol as a monomer has many special excellent properties and is widely used in fields such as carpets, engineering plastics, and clothing fabrics.

[0003] Catalytic selective hydrogenolysis of polyols containing two or more hydroxyl groups in the molecular structure to remove hydroxyl groups at specific positions, especially selectively removing secondary hydroxyl groups while retaining the two terminal hydroxyl groups, is an important method and technology for obtaining terminal diols. In this process, the selectivity of the catalyst is crucial. Literature reports that the catalysts commonly used for polyol hydrogenolysis are generally supported metal catalysts (CN102091624A, CN105669373A, CN105142776B, CN106883098B, CN102731259A, US20100113841A1), and the dispersion of metal components and the ability of the catalyst to chemisorb hydrogen are closely related to its activity and selectivity. For example, the literature (ChemCatChem, 2016, 8, 3663-3671; Journal of Catalysis, 2020, 388, 154-163; Applied Catalysis B-Environmental, 2019, 242, 410-421) elaborated on the influence of metal dispersion and hydrogen spillover on the reaction activity of glycerol hydrogenolysis to produce 1,3-propanediol through characterizations such as hydrogen chemisorption. The research shows that the reaction performance of the catalyst is positively correlated with the metal dispersion and the degree of hydrogen spillover on the catalyst. And the literature (ACS Sus.Chem.Eng. 2021, 9, 5705-5715) further verified that highly dispersed noble metal catalysts and effective hydrogen spillover are the prerequisites for obtaining higher glycerol hydrogenolysis reaction activity / selectivity.

[0004] Before a supported metal catalyst undergoes a hydrocracking or hydrogenation reaction, it generally needs to be activated through a pre-reduction process to enable the metal active component to have the ability to adsorb and dissociate hydrogen. The pre-reduction process of traditional polyol hydrocracking catalysts is carried out at high temperature directly in a hydrogen atmosphere. When hydrogen comes into contact with the catalyst, it is easy to generate a temperature runaway, resulting in local overheating that easily causes the catalyst to sinter. Eventually, the catalyst pre-reduced by this method often has a low raw material conversion rate and poor selectivity for the target product during the reaction process. Currently, the known patents using the hydrogen reduction activation method to treat polyol hydrocracking catalysts, such as the supported noble metal catalysts disclosed in Chinese patents CN106552623B, CN108607553B, CN106824191B, CN105618045B, CN110560057A, CN112169795A, etc., all need to be pre-reduced and activated in a hydrogen atmosphere, and the optimal activation temperature is above 300 °C, resulting in phenomena such as a decrease in the metal dispersion of the catalyst and a weakening of the ability to chemisorb hydrogen.

[0005] Since the pre-activation method of the supported catalyst has an important influence on the polyol hydrocracking reaction, it is necessary to innovate the activation method of the catalyst to improve the conversion rate of polyol and the yield of the target product and achieve industrial application. Summary of the Invention

[0006] The present invention relates to a pre-activation method for a supported metal catalyst for polyol hydrocracking. It mainly solves the problems that during the reduction process of traditional polyol hydrocracking catalysts directly in a hydrogen atmosphere, temperature runaway is easy to occur, resulting in local overheating that easily causes the catalyst to sinter, and the problems that the raw material conversion rate is low and the selectivity of the target product is low for the catalyst after direct reduction during the reaction process.

[0007] The present invention provides a method for preactivating a supported metal catalyst for hydrogenolysis of polyols, characterized in that the catalyst is composed of a carrier and active components A and B, the carrier is one or more of aluminum oxide, silicon oxide, zirconium oxide, titanium oxide or molecular sieve, the active component A is one or more of tungsten oxide, molybdenum oxide and rhenium oxide, and the active component B is one or more of precious metals ruthenium, rhodium, palladium, iridium and platinum. The catalyst preactivation method uses pure hydrogen or a mixed gas containing hydrogen and an inert gas, and liquid water as a reducing agent, through a fixed bed or slurry bed reactor, at a gas linear velocity of 0.1 to 1000 cm / min, preferably 1 to 100 cm / min; a liquid linear velocity of 0.001 to 10 cm / min, preferably 0.01 to 1 cm / min; a preactivation pressure of 0.5 to 10.0 MPa, preferably 4 to 8.0 MPa; a preactivation temperature of 80 to 500° C., preferably 100 to 250° C.; by means of hydrogen dissolved in the liquid contacting with the catalyst, the high-valent metal elements in the catalyst are slowly reduced to low-valent active metal elements or metal elements, wherein the active component A (tungsten oxide, molybdenum oxide) is reduced from high-valent metal oxides (WO3, MoO3, ReO3) to low-valent metal oxides (MOx, M=W, Mo, Re; 1 <x<3)、活性组分B(贵金属钌、铑、钯、铱、铂)的氧化物(二氧化钌、三氧化二铑、一氧化钯、二氧化铱、二氧化铂)被还原成低价态的金属氧化物(RuO a, 0 <a<4;RhO b ,0 <b<1.5;PdO c ,0 <c<2;IrO d ,0 <d<4;PtO e ,0 <e<4)或金属单质,所得到的催化剂其氢气化学吸附量均大于理论氢气化学吸附量。

[0008] The catalyst is prepared by an impregnation method, and the process is as follows: a precursor solution of active component A (one or more of tungsten oxide, molybdenum oxide, and rhenium oxide) (one or more of ammonium metatungstate, ammonium molybdate, or ammonium perrhenate) and a precursor solution of active component B (one or more of precious metals ruthenium, rhodium, palladium, iridium, and platinum) (one or more of ruthenium chloride, rhodium chloride, palladium chloride, chloroiridic acid, or chloroplatinic acid) are co-impregnated or impregnated step by step on a carrier (one or more of aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, or molecular sieve), the impregnation time is 1-72 hours (preferably 5-48 hours), dried in an oven at 80-120° C. for more than 2 hours, and air calcined in a muffle furnace at 300-900° C. (preferably 300-800° C.) for more than 2 hours (preferably 3-8 hours), and the obtained catalyst is recorded as B / A / carrier.

[0009] The pre-activation method of the catalyst is characterized in that when a mixed gas containing hydrogen and an inert gas is used as the reducing gas, the hydrogen content is greater than or equal to 0.1% and less than 100%. Preferably 50 - 100%; the inert gas is one or more of nitrogen, helium, and argon.

[0010] The catalyst is applied to the hydrogenolysis reaction of polyols. The polyol raw material is synthesized from any one of petroleum, biomass, or syngas, and the polyol is an organic compound containing two or more hydroxyl groups. The polyol hydrogenolysis reaction refers to the removal of one hydroxyl group from multiple hydroxyl groups in the molecular structure of the polyol, such as the hydrogenolysis of glycerol to 1,3 - propanediol, the hydrogenolysis of 1,4 - butanediol to n - butanol, the hydrogenolysis of 1,2 - propanediol to n - propanol, the hydrogenolysis of ethylene glycol to ethanol, the hydrogenolysis of tetrahydrofurfuryl alcohol to 1,5 - pentanediol, the hydrogenolysis of 5 - hydroxymethylfurfural to 1,6 - hexanediol, etc.

[0011] The pre - activation method of the supported metal catalyst for polyol hydrogenolysis involved in the present invention has the following advantages:

[0012] 1. By means of the hydrogen dissolved in water contacting the catalyst, it solves the problems that traditional polyol hydrogenolysis catalysts are prone to temperature runaway during the reduction process in a hydrogen atmosphere, resulting in local overheating, which easily causes the catalyst to sinter, the metal dispersion to decrease, and the ability to chemisorb hydrogen to weaken. It also solves the problems of low raw material conversion rate and low selectivity of the target product during the reaction of the directly reduced catalyst.

[0013] 2. Compared with the prior art, the pre - activated catalyst can significantly improve the conversion rate of polyols and the yield of the target product in the polyol hydrogenolysis reaction.

[0014] 3. Passing an aqueous solution during the pre - activation process can increase the hydroxyl groups on the catalyst surface, thereby promoting the occurrence of hydrogen spillover. That is, after the metal active component adsorbs and dissociates hydrogen, the dissociated hydrogen species will spill over to other species, thus increasing the hydrogen adsorption amount. This is also the reason why the hydrogen chemisorption amount of the pre - activated catalyst is greater than the theoretical hydrogen chemisorption amount. Specific Embodiments

[0015] The following embodiments will help to understand the present invention, but the protection scope of the present invention is not limited to these examples. The present invention will be described in detail with examples below:

[0016] Example 1

[0017] The catalyst used is Pt / WO3 / Al2O3, with a composition of Pt% = 2 wt%, W% = 10 wt%, and the rest being the Al2O3 support. The catalyst is prepared by the impregnation method. The specific preparation steps include: loading the precursor ammonium metatungstate solution of the active component tungsten oxide onto the support alumina by the equal-volume impregnation method, with an impregnation time of 15 h, drying in an oven at 120 °C for 5 h, and calcining in a muffle furnace at 500 °C for 5 h to obtain the composite oxide denoted as WO3 / Al2O3; loading the precursor chloroplatinic acid solution of the active component platinum onto WO3 / Al2O3 by the equal-volume impregnation method, with an impregnation time of 15 h, drying in an oven at 120 °C for 5 h, and calcining in a muffle furnace at 300 °C in air for 5 h to obtain the catalyst denoted as Pt / WO3 / Al2O3. The valence state of Pt is +4, and the valence state of W is +6.

[0018] A continuous fixed-bed reactor is used to pre-activate the catalyst. The specific process is as follows: filling 1 g of the catalyst, using a mixed gas of hydrogen and nitrogen (hydrogen volume content 50%) and pure water as raw materials, with a gas linear velocity of 50 cm / min; the (liquid) linear velocity of water is 0.4 cm / min, the pre-activation pressure is 7 MPa, and the pre-activation temperature is 200 °C. After pre-activation, the valence state of Pt is measured to be 0 by XPS, and the valence state of W is +5.3.

[0019] Example 2

[0020] Change the hydrogen volume content in the mixed gas of hydrogen and nitrogen to 80%, and keep other conditions the same as in Example 1. After pre-activation, the valence state of Pt is measured to be 0, and the valence state of W is +5.2.

[0021] Example 3

[0022] Change the mixed gas of hydrogen and nitrogen to pure hydrogen, and keep other conditions the same as in Example 1. After pre-activation, the valence state of Pt is measured to be 0, and the valence state of W is +5.2.

[0023] Example 4

[0024] Change the gas linear velocity of the mixed gas of hydrogen and nitrogen (hydrogen volume content 50%) to 25 cm / min, and keep other conditions the same as in Example 1. After pre-activation, the valence state of Pt is measured to be 0, and the valence state of W is +5.3.

[0025] Example 5

[0026] Change the gas linear velocity of the mixed gas of hydrogen and nitrogen (hydrogen volume content 50%) to 100 cm / min, and keep other conditions the same as in Example 1. After pre-activation, the valence state of Pt is measured to be 0, and the valence state of W is +5.3.

[0027] Example 6

[0028] The pre-activation pressure was changed to 3 MPa, and other conditions were the same as in Example 1. After pre-activation, the valence state of Pt was measured to be 1, and the valence state of W was +5.4.

[0029] Example 7

[0030] The pre-activation pressure was changed to 5 MPa, and other conditions were the same as in Example 1. After pre-activation, the valence state of Pt was measured to be 0, and the valence state of W was +5.3.

[0031] Example 8

[0032] The pre-activation temperature was changed to 300 °C, and other conditions were the same as in Example 1. After pre-activation, the valence state of Pt was measured to be 0, and the valence state of W was +5.2.

[0033] Example 9

[0034] The pre-activation temperature was changed to 500 °C, and other conditions were the same as in Example 1. After pre-activation, the valence state of Pt was measured to be 0, and the valence state of W was +5.1.

[0035] Example 10

[0036] The liquid linear velocity was 0.2 cm / min, and other conditions were the same as in Example 1. After pre-activation, the valence state of Pt was measured to be 0, and the valence state of W was +5.3.

[0037] Example 11

[0038] The liquid linear velocity was 0.8 cm / min, and other conditions were the same as in Example 1. After pre-activation, the valence state of Pt was measured to be 0, and the valence state of W was +5.3.

[0039] Example 12

[0040] The precursor of the catalyst 2 wt% Pt / WO3 / Al2O3 was changed to the precursor of Ir, i.e., chloroiridic acid solution, to prepare the catalyst 2 wt% Ir / WO3 / Al2O3 with the same noble metal mass. Other conditions were the same as in Example 1. After pre-activation, the valence state of Ir was measured to be 0, and the valence state of W was +5.3.

[0041] Example 13

[0042] The precursor of the catalyst 2 wt% Pt / WO3 / Al2O3 was changed to the precursor of Pd, i.e., palladium chloride solution, to prepare the catalyst 2 wt% Pd / WO3 / Al2O3 with the same noble metal mass. Other conditions were the same as in Example 1. After pre-activation, the valence state of Pd was measured to be 0, and the valence state of W was +5.2.

[0043] Example 14

[0044] The precursor of the catalyst 2 wt% Pt / WO3 / Al2O3 was changed to the precursor of Ir, i.e., chloroiridic acid solution, and the precursor of Re, i.e., ammonium perrhenate solution, to prepare a catalyst 2 wt% Ir / ReO3 / Al2O3 with the same mass of noble metal Ir. Re% = 10 wt%, and other conditions were the same as those in Example 1. After pre-activation, the valence state of Ir was measured to be 0, and the valence state of Re was +5.3.

[0045] Comparative Example 1

[0046] The catalyst was not pre-activated, and other conditions were the same as those in Example 1.

[0047] Comparative Example 2

[0048] No aqueous solution was introduced during the pre-activation process, and other conditions were the same as those in Example 1.

[0049] The results are shown in Table 1:

[0050]

[0051] The hydrogen chemisorption amount of the metal active component on the catalyst was measured using a Micromeritics Autochem II 2920 chemisorption instrument, and the detector was a thermal conductivity detector (TCD). The specific experimental operation was as follows: Approximately 100 mg of the above-mentioned pre-activated catalyst was loaded into a U-shaped quartz tube, hydrogen was passed through, and it was kept at 200 °C for 1 h for treatment. After the treatment, it was switched to helium, and the temperature was raised by 10 °C and purged for 30 min to remove the surface-adsorbed H species. Subsequently, the temperature was lowered to 50 °C, the gas path was switched to a 10% H2 / Ar mixed gas, and pulsed adsorption was carried out until saturation, and the actual hydrogen chemisorption amount of the metal active component on the catalyst could be obtained.

[0052] Calculation method for the theoretical hydrogen chemisorption amount of the catalyst:

[0053] Taking Pt / WO3 / Al2O3 in Example 1 as an example, Pt in each gram of catalyst was 2 wt%, and the molecular weight of Pt was 195, that is, the micromole number of Pt in each gram of catalyst was 102.56 μmol / g. Theoretically, the H / Pt adsorption ratio was 1:1, and hydrogen contained 2 Hs. Therefore, the chemisorption amount of H2 corresponding to Pt on the catalyst was 51.28 μmol / g.

[0054] As can be seen from Comparative Examples 1 and 2, the pre-activation method of the present invention plays a crucial role in increasing the hydrogen chemisorption amount of the active component of the supported metal catalyst. For the catalysts obtained without undergoing the pre-activation process or without introducing an aqueous solution during the pre-activation process, the actual hydrogen chemisorption amount is almost less than half of the theoretical amount. This is because without the pre-activation process, the active component of the catalyst exists in the form of high-valence oxides; while for the catalyst obtained without introducing an aqueous solution during the pre-activation process, although the active component of the catalyst exists in the low-valence form, when hydrogen comes into direct contact with the catalyst, it is prone to thermal runaway, resulting in local overheating, which easily causes the catalyst to agglomerate and sinter, reducing the metal dispersion and weakening the ability to chemisorb hydrogen.

[0055] Examples 1-11 investigated the effects of different hydrogen contents, gas hourly space velocity, liquid hourly space velocity, gas pressure, and pre-activation temperature on the pre-activation method of the Pt / WO3 / Al2O3 catalyst. From the results, it can be seen that the hydrogen chemisorption amounts of all the catalysts obtained by the pre-activation method are higher than the theoretical chemisorption amount.

[0056] Examples 12-14 investigated the hydrogen chemisorption ability of different supported metal catalysts treated by the pre-activation method of the present invention. From the results, it can be seen that the hydrogen chemisorption amounts of all the catalysts obtained by the pre-activation method are higher than the theoretical chemisorption amount.

[0057] Example 15

[0058] The pre-activation conditions were the same as those in Example 1. After the pre-activation was completed (i.e., 1 g of catalyst), the glycerol hydrocracking reaction to produce 1,3-propanediol was directly carried out in a fixed-bed reactor. The mass concentration of the glycerol aqueous solution was 50%, the reaction temperature was 200 °C, the reaction pressure was 7 MPa, the gas linear velocity was 50 cm / min, and the liquid linear velocity was 0.4 cm / min.

[0059] Example 16

[0060] The pre-activation conditions were the same as those in Example 2 (referring to the catalyst preparation and composition, and the pre-activation conditions are the same for Examples 17-28 below), and the other conditions were the same as those in Example 15 (referring to the glycerol hydrocracking process, and the same for Examples 17-28 below).

[0061] Example 17

[0062] The pre-activation conditions were the same as those in Example 3, and the other conditions were the same as those in Example 15.

[0063] Example 18

[0064] The pre-activation conditions were the same as those in Example 4, and the other conditions were the same as those in Example 15.

[0065] Example 19

[0066] The pre-activation conditions are the same as those in Example 5, and the other conditions are the same as those in Example 15.

[0067] Example 20

[0068] The pre-activation conditions are the same as those in Example 6, and the other conditions are the same as those in Example 15.

[0069] Example 21

[0070] The pre-activation conditions are the same as those in Example 7, and the other conditions are the same as those in Example 15.

[0071] Example 22

[0072] The pre-activation conditions are the same as those in Example 8, and the other conditions are the same as those in Example 15.

[0073] Example 23

[0074] The pre-activation conditions are the same as those in Example 9, and the other conditions are the same as those in Example 15.

[0075] Example 24

[0076] The pre-activation conditions are the same as those in Example 10, and the other conditions are the same as those in Example 15.

[0077] Example 25

[0078] The pre-activation conditions are the same as those in Example 11, and the other conditions are the same as those in Example 15.

[0079] Example 26

[0080] The precursor of the catalyst 2wt% Pt / WO3 / Al2O3 was changed to the precursor of Ir, the chloroiridic acid solution, to prepare the catalyst 2wt% Ir / WO3 / Al2O3 with the same noble metal mass. The pre-activation conditions are the same as those in Example 1, and the other conditions are the same as those in Example 15.

[0081] Example 27

[0082] The precursor of the catalyst 2wt% Pt / WO3 / Al2O3 was changed to the precursor of Rh, the rhodium chloride solution, to prepare the catalyst 2wt% Rh / WO3 / Al2O3 with the same noble metal mass. The pre-activation conditions are the same as those in Example 1, and the other conditions are the same as those in Example 15.

[0083] Example 28

[0084] The catalyst of 2 wt% Pt / WO3 / Al2O3 precursor was changed to the precursor solution of iridium chloride for Ir and ammonium perrhenate solution for Re, and the catalyst of 2 wt% Ir / ReO3 / Al2O3 with the same noble metal mass was prepared, where Re% = 10 wt%. The pre-activation conditions were the same as those in Example 1, and other conditions were the same as those in Example 15.

[0085] Comparative Example 3

[0086] The catalyst was not pre-activated (referring to the catalyst prepared in Example 1, just without pre-activation), and other conditions were the same as those in Example 15.

[0087] Comparative Example 4

[0088] The catalyst was not pre-activated, and other conditions were the same as those in Example 26.

[0089] Comparative Example 5

[0090] No aqueous solution was introduced during the pre-activation process (referring to the catalyst prepared in Example 1), and other conditions were the same as those in Example 15.

[0091] Comparative Example 6

[0092] No aqueous solution was introduced during the pre-activation process (referring to the catalyst prepared in Example 1), and the gas linear velocity was 100 cm / min, and other conditions were the same as those in Example 15.

[0093] Comparative Example 7

[0094] No aqueous solution was introduced during the pre-activation process (referring to the catalyst prepared in Example 1), the gas linear velocity was 100 cm / min, and the pre-activation pressure was changed to 3 MPa, and other conditions were the same as those in Example 15.

[0095] Comparative Example 8

[0096] Pure water was changed to 80% water - 20% methanol, other pre-activation conditions were the same as those in Example 1, and the reaction conditions were the same as those in Example 15.

[0097] Comparative Example 9

[0098] Pure water was changed to 80% water - 20% ethanol, other pre-activation conditions were the same as those in Example 1, and the reaction conditions were the same as those in Example 15.

[0099] Comparative Example 10

[0100] Pure water was changed to 90% water - 10% ethanol, other pre-activation conditions were the same as those in Example 1, and the reaction conditions were the same as those in Example 15.

[0101] Comparative Example 11

[0102] Change pure water to 80% water - 20% ethylene glycol, and keep other pre - activation conditions the same as in Example 1 and reaction conditions the same as in Example 15.

[0103] Table 2 Performance comparison of glycerol conversion to 1,3 - propanediol under different pre - activation conditions

[0104]

[0105]

[0106] It can be seen from Comparative Examples 3 and 4 that the pre - activation treatment plays a crucial role in the catalytic performance of the catalyst. The catalyst without pre - activation has almost no activity.

[0107] It can be seen from Comparative Examples 5 - 7 that passing an aqueous solution during the pre - activation treatment plays a crucial role in the catalytic performance of the catalyst. The performance of the pre - activated catalyst without passing an aqueous solution is poor.

[0108] It can be seen from Comparative Examples 5, 8 - 11 that passing a pure aqueous solution during the pre - activation treatment plays a crucial role in the catalytic performance of the catalyst; when passing an alcohol - aqueous solution during the pre - activation treatment, as the carbon number of the alcohol increases, the performance of the pre - activated catalyst shows a downward trend; in addition, when passing a polyol - aqueous solution during the pre - activation treatment, its catalytic performance is even worse.

[0109] Examples 15 - 17 investigated the influence of the hydrogen content during the pretreatment process on the activity of the Pt / WO3 / Al2O3 catalyst. From the results, we can see that when the hydrogen content during the pretreatment process is 50%, the catalytic activity is the best: both the glycerol conversion rate and the yield of 1,3 - propanediol are the highest.

[0110] Examples 15, 18, 19 investigated the influence of the gas linear velocity during the pretreatment process on the activity of the Pt / WO3 / Al2O3 catalyst. From the results, we can see that the optimal gas linear velocity is 50 cm / min.

[0111] Examples 15, 20, 21 investigated the influence of the pre - activation pressure during the pretreatment process on the activity of the Pt / WO3 / Al2O3 catalyst. From the results, we can see that as the pre - activation pressure increases from 3 MPa to 7 MPa, both the glycerol conversion rate and the yield of 1,3 - propanediol are continuously increasing. Thus, it can be concluded that the catalytic activity is the best when the pre - activation pressure is 7 MPa.

[0112] Examples 15, 22, and 23 investigated the effect of the pre-activation temperature during the pre-treatment process on the activity of the Pt / WO3 / Al2O3 catalyst. From the results, it can be seen that as the pre-activation temperature increased from 200 °C to 500 °C, the glycerol conversion rate and the yield of 1,3-propanediol showed a downward trend. Thus, it was concluded that the optimal pre-activation temperature was 200 °C.

[0113] Examples 15, 24, and 25 investigated the effect of the liquid linear velocity during the pre-treatment process on the activity of the Pt / WO3 / Al2O3 catalyst. From the results, it can be seen that the optimal liquid linear velocity was 0.5 cm / min.

[0114] Examples 15, 26, 27, and 28 investigated the effect of different supported metal catalysts after pre-treatment on the glycerol hydrogenolysis reaction. From the results, it can be seen that the catalysts after pre-treatment significantly improved both the catalytic activity for glycerol and the yield of 1,3-propanediol.

[0115] From the above results, it can be seen that after pre-activating the catalyst used in the present invention by the pre-activation method of the present invention, both the conversion rate of glycerol and the yield of the target product 1,3-propanediol can be greatly improved, indicating that the method of the present invention has a significant effect on the reaction of glycerol hydrogenolysis to produce 1,3-propanediol.

[0116] Example 29

[0117] The pre-activation conditions were the same as those in Example 1 (referring to the catalyst preparation and composition, and the same applies to Examples 30 - 32 below). After the pre-activation was completed, the hydrogenolysis reaction of 1,4-butanediol to n-butanol was directly carried out in a fixed-bed reactor. The mass concentration of the 1,4-butanediol aqueous solution was 50%, the reaction temperature was 160 °C, the reaction pressure was 7 MPa, the gas linear velocity was 50 cm / min, and the liquid linear velocity was 0.5 cm / min. The conversion rate of 1,4-butanediol reached 90%, and the yield of n-butanol was 90%.

[0118] Example 30

[0119] The pre-activation conditions were the same as those in Example 1. After the pre-activation was completed, the hydrogenolysis reaction of 1,2-propanediol to n-propanol was directly carried out in a fixed-bed reactor. The mass concentration of the 1,2-propanediol aqueous solution was 50%, the reaction temperature was 160 °C, the reaction pressure was 7 MPa, the gas linear velocity was 50 cm / min, and the liquid linear velocity was 0.5 cm / min. The conversion rate of 1,2-propanediol reached 93%, and the yield of n-propanol was 92%.

[0120] Example 31

[0121] The pre-activation conditions are the same as those in Example 1. After the pre-activation is completed, the hydrogenolysis of tetrahydrofurfuryl alcohol to 1,5-pentanediol is directly carried out on a fixed-bed reactor. The mass concentration of the tetrahydrofurfuryl alcohol aqueous solution is 20%, the reaction temperature is 140 °C, the reaction pressure is 5 MPa, the gas linear velocity is 50 cm / min, and the liquid linear velocity is 0.5 cm / min. The conversion rate of tetrahydrofurfuryl alcohol reaches 95%, and the yield of 1,5-pentanediol is 90%.

[0122] Example 32

[0123] The pre-activation conditions are the same as those in Example 1. After the pre-activation is completed, the hydrogenolysis of 5-hydroxymethylfurfural to 1,6-hexanediol is directly carried out on a fixed-bed reactor. The mass concentration of the 5-hydroxymethylfurfural aqueous solution is 10%, the reaction temperature is 140 °C, the reaction pressure is 5 MPa, the gas linear velocity is 50 cm / min, and the liquid linear velocity is 0.5 cm / min. The conversion rate of 5-hydroxymethylfurfural reaches 95%, and the yield of 1,6-hexanediol is 90%.

[0124] Comparative Example 12

[0125] There is no pre-activation process (which means that the catalyst preparation and composition are the same as those in Example 1). The catalyst is directly used for the hydrogenolysis of 1,2-propanediol to n-propanol on a fixed-bed reactor. The mass concentration of the 1,2-propanediol aqueous solution is 50%, the reaction temperature is 160 °C, the reaction pressure is 7 MPa, the gas linear velocity is 50 cm / min, and the liquid linear velocity is 0.5 cm / min. The conversion rate of 1,2-propanediol reaches 41%, and the yield of n-propanol is 60%. From the results of Examples 29 - 32, it can be seen that the catalyst obtained by the pre-activation method involved in the present invention has significant effects on the hydrogenolysis reactions of polyols such as glycerol, butanediol, and propanediol, while the catalyst without the pre-activation process has relatively low activity and selectivity for the hydrogenolysis ability of polyols.

Claims

1. Application of a catalyst treated by a pre-activation method in a polyol hydrocracking reaction, wherein the polyol hydrocracking reaction is the hydrocracking of glycerol to 1,3-propanediol, the hydrocracking of 1,4-butanediol to n-butanol, the hydrocracking of 1,2-propanediol to n-propanol, and the hydrocracking of ethylene glycol to ethanol; characterized in that: The catalyst is composed of a carrier and active components A and B loaded on the carrier, wherein the carrier is one or more of aluminum oxide, silicon oxide, zirconium oxide, titanium oxide or molecular sieve, the active component A is one or more of WO3, MoO3 and ReO3, and the active component B is one or more of ruthenium dioxide, rhodium trioxide, palladium oxide, iridium dioxide and platinum dioxide; The catalyst preactivation method uses pure hydrogen or a mixture of hydrogen and inert gas, and liquid water as a reducing agent, through a fixed bed or slurry bed reactor, the pure hydrogen or mixed gas linear velocity is 0.1 to 1000 cm / min; the liquid water linear velocity is 0.001 to 10 cm / min, the preactivation pressure is 0.5 to 10.0 MPa, and the preactivation temperature is 80 to 500°C; By controlling the pressure and temperature, water is passed through the reactor in a partially or completely liquid form, and the water is contacted with the catalyst by means of hydrogen dissolved in the liquid, so that the high-valent metal elements in the catalyst are reduced to low-valent active metal elements or metal elements, wherein the active component A is reduced from a high-valent metal oxide to a low-valent metal oxide; the high-valent metal oxide of the active component A is WO3, MoO3, ReO3, and the low-valent metal oxide of the active component A is MOx, M = W, Mo, Re; 1< x<3; The oxide of active component B is reduced to a metal element; the oxide of active component B is ruthenium dioxide, rhodium trioxide, palladium monoxide, iridium dioxide, and platinum dioxide.

2. The use according to claim 1, characterized in that: In the catalyst preactivation method, the linear velocity of pure hydrogen or mixed gas is 1 to 100 cm / min; the linear velocity of liquid water is 0.01 to 1 cm / min; the preactivation pressure is 4 to 8.0 MPa; and the preactivation temperature is 100 to 250°C.

3. The application according to claim 1, wherein: The catalyst is prepared by an impregnation method, wherein the precursor solution of active component A and the precursor solution of active component B are co-impregnated or impregnated step by step on the carrier, the impregnation time is 1-72 h, dried in an oven at 80-120° C. for more than 2 h, and calcined in air at 300-900° C. in a muffle furnace for more than 2 h. The obtained catalyst is recorded as B / A / carrier; Among them, the precursor solution of active component A is one or more of ammonium metatungstate, ammonium molybdate or ammonium perrhenate; the precursor solution of active component B is one or more of ruthenium chloride, rhodium chloride, palladium chloride, chloroiridic acid or chloroplatinic acid, and the carrier is one or more of aluminum oxide, silicon oxide, zirconium oxide, titanium oxide or molecular sieve.

4. The application according to claim 3, wherein: The impregnation time is 5-48 h, the catalyst is dried in an oven at 80-120° C. for more than 2 h, and calcined in air at 300-800° C. in a muffle furnace for 3-8 h. The obtained catalyst is recorded as B / A / support.

5. The application according to claim 1, wherein: When a mixed gas containing hydrogen and inert gas is used as the reducing gas, the volume content of hydrogen is greater than or equal to 0.1% and less than 100%; the inert gas is one or more of nitrogen, helium and argon.

6. The application according to claim 1 or 5, characterized in that: When a mixed gas containing hydrogen and inert gas is used as the reducing gas, the volume content of hydrogen is 50-100%.

7. Use of a catalyst treated by a pre-activation method in the hydrogenolysis of tetrahydrofurfuryl alcohol to 1,5-pentanediol or in the hydrogenolysis of 5-hydroxymethylfurfural to 1,6-hexanediol; characterized in that: The catalyst is composed of a carrier and active components A and B loaded on the carrier, wherein the carrier is one or more of aluminum oxide, silicon oxide, zirconium oxide, titanium oxide or molecular sieve, the active component A is one or more of WO3, MoO3 and ReO3, and the active component B is one or more of ruthenium dioxide, rhodium trioxide, palladium oxide, iridium dioxide and platinum dioxide; The catalyst preactivation method uses pure hydrogen or a mixture of hydrogen and inert gas, and liquid water as a reducing agent, through a fixed bed or slurry bed reactor, the pure hydrogen or mixed gas linear velocity is 0.1 to 1000 cm / min; the liquid water linear velocity is 0.001 to 10 cm / min, the preactivation pressure is 0.5 to 10.0 MPa, and the preactivation temperature is 80 to 500°C; By controlling the pressure and temperature, water is passed through the reactor in a partially or completely liquid form, and the water is contacted with the catalyst by means of hydrogen dissolved in the liquid, so that the high-valent metal elements in the catalyst are reduced to low-valent active metal elements or metal elements, wherein the active component A is reduced from a high-valent metal oxide to a low-valent metal oxide; the high-valent metal oxide of the active component A is WO3, MoO3, ReO3, and the low-valent metal oxide of the active component A is MOx, M = W, Mo, Re; 1< x<3; The oxide of active component B is reduced to a metal element; the oxide of active component B is ruthenium dioxide, rhodium trioxide, palladium monoxide, iridium dioxide, and platinum dioxide.

8. The use according to claim 7, characterized in that: In the catalyst preactivation method, the linear velocity of pure hydrogen or mixed gas is 1 to 100 cm / min; the linear velocity of liquid water is 0.01 to 1 cm / min; the preactivation pressure is 4 to 8.0 MPa; and the preactivation temperature is 100 to 250°C.

9. The application according to claim 7, characterized in that: The catalyst is prepared by an impregnation method, wherein the precursor solution of active component A and the precursor solution of active component B are co-impregnated or impregnated step by step on the carrier, the impregnation time is 1-72 h, dried in an oven at 80-120° C. for more than 2 h, and calcined in air at 300-900° C. in a muffle furnace for more than 2 h. The obtained catalyst is recorded as B / A / carrier; Among them, the precursor solution of active component A is one or more of ammonium metatungstate, ammonium molybdate or ammonium perrhenate; the precursor solution of active component B is one or more of ruthenium chloride, rhodium chloride, palladium chloride, chloroiridic acid or chloroplatinic acid, and the carrier is one or more of aluminum oxide, silicon oxide, zirconium oxide, titanium oxide or molecular sieve.

10. The application according to claim 9, characterized in that: The impregnation time is 5-48 h, the catalyst is dried in an oven at 80-120°C for more than 2 h, and the catalyst is calcined in air at 300-800°C in a muffle furnace for 3-8 h. The obtained catalyst is recorded as B / A / support.

11. The application according to claim 7, wherein: When a mixed gas containing hydrogen and an inert gas is used as the reducing gas, the volume content of hydrogen is greater than or equal to 0.1% and less than 100%; the inert gas is one or more of nitrogen, helium, and argon.

12. The application according to claim 7 or 11, characterized in that: When a mixed gas containing hydrogen and an inert gas is used as the reducing gas, the volume content of hydrogen is 50-100%.

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