CN104689816A - Palladium monatomic catalyst, preparation of palladium monatomic catalyst and application of palladium monatomic catalyst in acetylene hydrogenation reaction - Google Patents

Abstract

The invention discloses a palladium monatomic catalyst, preparation of the palladium monatomic catalyst and application of the palladium monatomic catalyst in acetylene hydrogenation reaction. The palladium monatomic catalyst is prepared by the following steps: with Pd as the active component and ZnO as a carrier, dipping, and carrying out high-temperature reduction to form an alloyed monatomic catalyst. Under the conditions of low temperature, wide temperature range (60-300 DEG C) and high space velocity (such as 180000mL/g.h) and in pure acetylene atmosphere and acetylene atmosphere with a great amount of acetylene, a small amount of the catalyst (such as 10mg) has excellent activity, selectivity and stability. The invention provides a preparation method of the palladium monatomic catalyst. The preparation method is simple and feasible, very good catalytic performance is shown in preparation of acetylene by selectively hydrogenating in the acetylene and the industrial application prospect is good.

Description

The monatomic catalyst of a kind of palladium and preparation thereof and the application in acetylene hydrogenation reaction

Technical field

The invention belongs to technological invention field, be specifically related to the monatomic Catalysts and its preparation method of a kind of palladium and the application in preparing ethylene by selective hydrogenation of acetylene reaction.

Background technology

The polyethylene obtained by vinyl polymerization is a kind of most widely used macromolecular material.Industrial, ethene is mainly through hydrocarbon cracking, and the methods such as methanol-to-olefins obtain, but obtained ethylene raw material gas all contains a small amount of acetylene usually.The existence of trace acetylene can make the very fast poisoning and deactivation of the ziegler natta catalyst of vinyl polymerization, thus affects the poly degree of polymerization and affect its material character, and meanwhile, in High-pressure Polyethylene Production process, the excessive accumulation of acetylene, even sets off an explosion.Therefore, acetylene a small amount of in ethylene raw material gas must be down to ppm level and be used further to polymerization.

Catalysis selective hydrogenation is a kind of method removing acetylene most effectively, and the method not only can remove acetylene impurities a small amount of in unstripped gas, is converted into available ethylene raw simultaneously.Industrial adopted Pd is catalyst based at present, has good activity, selective and stability when acetylene low-conversion.But when acetylene height transforms, ethene and the ethylene raw material gas of generation understand excessive hydrogenation usually, thus cause and optionally sharply decline.This is mainly because this reaction is consecutive reaction (C ₂h ₂→ C ₂h ₄→ C ₂h ₆), therefore, how to avoid the excessive hydrogenation of ethene in intermediate product ethene and unstripped gas to become the key issue of catalyst preparing and application.

This patent is prepared the monatomic catalyst of Pd/ZnO and is applied to the selective hydrogenation reaction of acetylene.This catalyst shows superior catalytic performance in the selective hydrogenation of acetylene, has good activity, selective and stability.

Summary of the invention

The object of the invention is to provide a kind of for producing ethylene with acetylene hydrogenation Catalysts and its preparation method, and this catalyst is the monatomic catalyst of palladium, has superior catalytic performance.

For achieving the above object, the technical solution used in the present invention is as follows:

Catalyst activity component of the present invention is Pd, carrier be easily and Pd form the ZnO of alloy, the load capacity of Pd is 0.3-4%.Preparation method is equi-volume impregnating.

The preparation method of described acetylene hydrogenation catalyst, comprises following step:

1) maceration extract is configured: with nitric acid and deionized water dissolving palladium nitrate, obtained maceration extract; Palladium nitrate mass concentration is 8-100mgPd/mL;

2) incipient impregnation: the ZnO carrier through 120-140 DEG C of heat treatment 6-10 hour is mixed with maceration extract, floods 24-36h under room temperature, obtain catalyst precursor;

3) heat treatment: by catalyst precursor 120-200 DEG C of dry 6-15h in drying box, then 300-400 DEG C of calcining 2-6h in Muffle furnace, is finally cooled to room temperature;

4) reduction activation: at volume content 5-50%H ₂in/He atmosphere, 300-600 DEG C of reduction forms the monatomic catalyst of alloying in 1-3 hour.

Selective hydrogenation of acetylene reaction adopts the method for in-situ reducing.Catalyst is at 5-50%H ₂in/He atmosphere, at 300-600 DEG C, reduce 1-3h, after being down to reaction temperature, carry out acetylene hydrogenation reaction.

Described catalytic hydrogenation reaction, reaction atmosphere comprises: simple acetylene atmosphere (C ₂h ₂account for 0.5-3%, H ₂account for 5-20%, all the other are inert gas) and ethene exist acetylene atmosphere (C ₂h ₂account for 0.5-3%, C ₂h ₄account for 30-60%, H ₂account for 5-20%, all the other are inert gas).Reaction temperature is 20-300 DEG C.Catalyst amount is 5-30mg, and mixed gas flow is 10-100mL/min, and air speed is 90,000-360,000mL/g.h.

Under the operating conditions described above, the monatomic catalyst of palladium shows superior catalytic performance in selective hydrogenation of acetylene reaction, is embodied in following 4 points:

1. comparatively low reaction temperatures (80 DEG C), takes into account selective (~ 85%) and active (~ 90%).

2., in wide temperature range (70-290 DEG C), excellent activity is maintained, selective, stability.Industry acetylene hydrogenation purify ethylene technique is carried out at certain temperature range window, so this point no less important.

3. the acetylene atmosphere of simple acetylene atmosphere and ethene existence, acetylene hydrogenation is selective all fine.

4. temperature raises, active rising, selective not decline, and slowly raises.This is the situation of seldom seeing in consecutive reaction.

In description of the present invention and in following embodiment and comparative example, optionally define because reaction atmosphere is different different:

Simple acetylene atmosphere (C ₂h ₂account for 0.5-3%, H ₂account for 5-20%, all the other are inert gas)

$S=\frac{C_2{H}_4\left(\mathrm{out}\right)-C_2{H}_4\left(\mathrm{in}\right)}{C_2{H}_2\left(\mathrm{in}\right)-C_2{H}_2\left(\mathrm{out}\right)}\×100\%...1$

$S_{\mathrm{gas}}=\frac{C_2{H}_4\left(\mathrm{out}\right)-C_2{H}_4\left(\mathrm{in}\right)}{C_2{H}_4\left(\mathrm{out}\right)-C_2{H}_4\left(\mathrm{in}\right)+C_2{H}_6\left(\mathrm{out}\right)-C_2{H}_6\left(\mathrm{in}\right)}\×100\%...2$

Acetylene atmosphere (the C that ethene exists ₂h ₂account for 0.5-3%, C ₂h ₄account for 30-60%, H ₂account for 5-20%, all the other are inert gas)

$S=(1-\frac{C_2{H}_6\left(\mathrm{out}\right)-C_2{H}_6\left(\mathrm{in}\right)}{C_2{H}_2\left(\mathrm{in}\right)-C_2{H}_2\left(\mathrm{out}\right)})\×100\%...3$

Illustrate:

1. pure acetylene atmosphere provides two kinds of selective calculation methods, and wherein formula 1 is optionally definition, the most real computational methods, and formula 2 considers gas-phase product distribution situation, embodies whether excessive hydrogenation generates ethane.

2. ethene exist lower selective be indirectly computational methods, because ethene in the ethene relative raw material gas that generated by acetylene is few, adopt formula 1 error of calculation larger, calculate according to formula 1 in the specific embodiment of the invention, selective have more than 100%, so adopt formula 3 to express a large amount of ethene there is the selective of lower acetylene hydrogenation.Optionally negative value represents except acetylene hydrogenation generates ethane, and the ethene in unstripped gas also a large amount of hydrogenation generates ethane.

Accompanying drawing explanation

Fig. 1 is the infared spectrum of embodiment 1CO at Catalyst Adsorption;

Fig. 2 is embodiment 7 reaction result figure;

Fig. 3 is comparative example 3 reaction result figure;

Fig. 4 is embodiment 12 reaction result figure;

Fig. 5 is comparative example 6 reaction result figure.

Detailed description of the invention

Below in conjunction with specific embodiment, the present invention is described in further detail.Protection scope of the present invention is not limited with detailed description of the invention, but is limited by claim.

Embodiment 1

1) maceration extract is configured: with nitric acid and deionized water dissolving palladium nitrate, obtained maceration extract; Palladium nitrate concentration is 80mgPd/mL;

2) incipient impregnation: mix through 120 DEG C of heat treatments ZnO carrier of 8 hours with maceration extract, flood 30h under room temperature, obtain catalyst precursor;

3) heat treatment: by catalyst precursor 120 DEG C of dry 8h in drying box, then 400 DEG C of calcining 3h in Muffle furnace, are finally cooled to room temperature;

4) reduction activation: at volume content 10%H ₂in/He atmosphere, 300 DEG C of reduction obtain monatomic catalyst in 1 hour.CO shows at the infared spectrum (Fig. 1) of Catalyst Adsorption: catalyst P d mainly exists with monatomic form.(illustrate: 1890cm ^-1with 2060cm ^-1adsorption peak is attributed to the bridge-type of CO on Pd respectively and line formula is adsorbed.Have the Pd atom that two or more is connected in bridge-type CO absorption proof catalyst, Pd/ZnO catalyst, mainly based on line formula, illustrates that catalyst mainly exists with monatomic form.）

Embodiment 2

Carry out acetylene hydrogenation reaction under the catalyst normal pressure obtained with embodiment 1,10mg catalyst mixes with 100mg quartz sand, volume content 10%H ₂300 DEG C of reduction 1h in/He atmosphere, be then down to 60 DEG C and carry out acetylene hydrogenation reaction, unstripped gas composition (volume content) is 2%C ₂h ₂, 20%H ₂, He is Balance Air, and gas flow is 30mL/min, air speed 180,000mL/g.h, and unstripped gas and product analysis adopt Agilent gas-chromatography, hydrogen flame detector.Reaction time 12h, reaction result lists in table 1.

Embodiment 3

Difference from Example 2 is: reaction temperature becomes 80 DEG C from 60 DEG C, and reaction result lists in table 1.

Embodiment 4

Difference from Example 2 is: reaction temperature becomes 110 DEG C from 60 DEG C, and reaction result lists in table 1.

Embodiment 5

Difference from Example 2 is: reaction temperature becomes 150 DEG C from 60 DEG C, and reaction result lists in table 1.

Embodiment 6

Difference from Example 2 is: reaction temperature becomes 200 DEG C from 60 DEG C, and reaction result lists in table 1.

Comparative example 1

Difference from Example 3 is: catalyst becomes 5mg1%-Pd/Al from 10mg1%-Pd/ZnO ₂o ₃, reaction result lists in table 1.

Comparative example 2

With comparative example 1 difference be: reaction temperature becomes 40 DEG C from 80 DEG C, and reaction result lists in table 1.

Table 1

Embodiment 7

Difference from Example 2 is: reaction temperature becomes 20-230 DEG C of temperature programming from being stabilized in 60 DEG C, and reaction result lists in Fig. 2.

Comparative example 3

Difference from Example 7 is: catalyst becomes 5mg1%-Pd/Al from 10mg1%-Pd/ZnO ₂o ₃, temperature becomes 20-90 DEG C from 20-230 DEG C, and reaction result lists in Fig. 3.

Visible:

1. 1%-Pd/ZnO catalyst is 80 DEG C time, conversion of alkyne 96%, ethylene selectivity 74%, gaseous ethene selective 93%.Lower temperature takes into account activity and selectivity.

2. along with the rising of temperature, conversion of alkyne is close to 100%, and ethylene selectivity is slowly increased to 88%, and ethylene gas phase selectivity remains essentially in 95%.In wide temperature range (70-290 DEG C), maintain excellent activity, selective, stability.

3. with 1%-Pd/Al ₂o ₃compare, 1%-Pd/ZnO high temperature reduction forms monatomic catalyst, and good ethene suppressing deep hydrogenation generates ethane, and selective large degree improves.

Embodiment 8

Difference from Example 3 is: catalyst is different batches catalyst, and the reaction time is 18h, and reaction result lists in table 2.

Embodiment 9

Difference from Example 8 is: reduction temperature becomes 400 DEG C from 300 DEG C, and reaction result lists in table 2.

Embodiment 10

Difference from Example 8 is: reduction temperature becomes 500 DEG C from 300 DEG C, and reaction result lists in table 2.

Comparative example 4

Difference from Example 3 is: reduction temperature becomes 100 DEG C from 300 DEG C, and reaction result lists in table 2.

Table 2

Visible, 1%-Pd/ZnO only forms monatomic catalyst at high temperature reduction, selectively just increases substantially.

Embodiment 11

Difference from Example 4 is: unstripped gas is except 2%C ₂h ₂, 20%H ₂outward, 40%C is also had ₂h ₄, reaction result lists in table 3.

Comparative example 5

With embodiment 11 difference be: catalyst becomes 5mg1%-Pd/Al from 10mg1%-Pd/ZnO ₂o ₃, reaction temperature becomes 50 DEG C from 80 DEG C, and reaction result lists in table 3.

Table 3

Embodiment 12

With embodiment 11 difference be: reaction temperature becomes 30-290 DEG C of temperature programming from being stabilized in 80 DEG C, and reaction result lists in Fig. 4.

Comparative example 6

With embodiment 12 difference be: catalyst becomes 5mg1%-Pd/Al from 10mg1%-Pd/ZnO ₂o ₃, reaction temperature becomes 20-150 DEG C from 30-290 DEG C, and reaction result lists in Fig. 5.

Visible, the monatomic catalyst of Pd/ZnO not only shows excellent catalytic performance in simple acetylene hydrogenation reaction, in the acetylene hydrogenation that ethene exists, have superior activity equally, selective.

Claims (7)

1. the monatomic catalyst of palladium, is characterized in that: the carrier selected by catalyst be easily and palladium form the ZnO of alloy; Active constituent is palladium, and palladium is scattered in carrier with monatomic form, and the percentage composition of the palladium in catalyst is 0.3-4%.

2. a preparation method for the monatomic catalyst of palladium described in claim 1, is characterized in that: catalyst adopts infusion process to prepare, and comprises the following steps:

1) maceration extract is configured: with nitric acid and deionized water dissolving palladium nitrate, obtained maceration extract; Palladium nitrate mass concentration is 8-100mgPd/mL;

2) incipient impregnation: the ZnO carrier through 120-140 DEG C of heat treatment 6-10 hour is mixed with maceration extract, floods 24-36h under room temperature, obtain catalyst precursor;

3) heat treatment: by catalyst precursor 120-200 DEG C of dry 6-15h in drying box, then 300-400 DEG C of calcining 2-6h in Muffle furnace, is finally cooled to room temperature;

4) reduction activation: at volume content 5-50%H ₂in/He atmosphere, 300-600 DEG C of reduction forms the monatomic catalyst of alloying in 1-3 hour.

3. an application for the monatomic catalyst of palladium described in claim 1, is characterized in that:

The monatomic catalyst of described palladium is used in preparing ethylene by selective hydrogenation of acetylene reaction.

4. according to application according to claim 3, it is characterized in that: catalytic hydrogenation reaction atmosphere is the acetylene atmosphere under simple acetylene atmosphere or ethene exist.

5. according to application according to claim 4, it is characterized in that: described simple acetylene atmosphere, C ₂h ₂account for 0.5-3%, H ₂account for 5-20%, all the other are inert gas; Acetylene atmosphere under described ethene exists, C ₂h ₂account for 0.5-3%, C ₂h ₄account for 30-60%, H ₂account for 5-20%, all the other are inert gas.

6. according to application according to claim 3, it is characterized in that: selective hydrogenation of acetylene reaction temperature 20-300 DEG C.

7., according to application according to claim 3, it is characterized in that: acetylene hydrogenation catalyst consumption 5 ?30mg, the gas flow of reaction atmosphere be 10 ?100mL/min, air speed 90,000 ?360,000mL/g.h.