EP2539043A1

EP2539043A1 - Method for separating components of natural gas or petroleum gas using inorganic porous membranes

Info

Publication number: EP2539043A1
Application number: EP11704460A
Authority: EP
Inventors: Sebastian Wohlrab; Udo Lubenau; Christine Hecker
Original assignee: Dbi-Gastechnisches Institut Freiberg GmbH; Leibniz-Institut fur Katalyse Ev An Der Universitat Rostock
Current assignee: Dbi-Gastechnisches Institut Freiberg GmbH; Leibniz-Institut fur Katalyse Ev An Der Universitat Rostock
Priority date: 2010-02-26
Filing date: 2011-02-22
Publication date: 2013-01-02
Also published as: DE102010009542A1; WO2011104226A1

Abstract

The invention relates to a method for separating components of natural gas or petroleum gas using inorganic porous membranes, wherein higher hydrocarbons can be effectively continuously separated without extensive cooling of the gases and without sweep gas at high gas pass-through rates and at practical pressures of methane. According to the method, feed pressures of greater than 5 bar are used, wherein the pressure on the permeate side is lower than that on the feed side, allowing adsorption and pressure-driven increased adsorption and condensation of the higher hydrocarbons on and in the pores of the membrane, wherein mesoscopically and macroscopically impermeable inorganic membranes are used, having microchannels having pore sizes in the range of the hydrocarbons to be separated.

Description

Process for the separation of natural gas or petroleum gas components from inorganic porous membranes Field of application of the invention

The invention relates to a method for the separation of natural gas or Erdölbegleitgas components of inorganic porous membranes, in which higher hydrocarbons to C ₆ from natural gas and associated gas are separated effectively without extensive expansion and cooling using membrane technology continuously.

State of the art

Natural gas at their Förderstelie sometimes considerable amounts of undesirable higher hydrocarbons (HKW), which must be removed before transport from the pump to the consumer in order to avoid malfunctioning by formation of gas hydrates. Petroleum feed gases still have significantly higher amounts of HKW, although these are currently hardly used.

A common treatment process of natural gas is currently the adsorptive drying mitteis glycol and the removal of higher hydrocarbons by deep-freeze condensation. Deep-freeze condensation is a process and energy-consuming process which, after expansion, causes a compression of the delivered gas. In some cases, an additional pre-treatment of the gas flow is required.

The disadvantage of swelling polymer-based membranes and thus loss of selectivity membranes of inorganic non-metallic materials do not have. Further advantages are their high chemical resistance, pressure and pressure swing resistance as well as thermal stability. A prerequisite for a selective separation is a uniform pore size of the inorganic membrane material in the molecular size of the components to be separated. Therefore, zeolite membranes are suitable because they have an inherent, defined pore system. The hydrophobic silicalite or low-aluminum ZSM-5 from the group of MFI zeolites is particularly suitable for the separation of non-polar components from natural gases.

For example, WO 94/01209 describes the synthesis of dense ZSM-5 layers and their use in the selective adsorption of, inter alia, hydrocarbons up to an applied feed pressure of 100 kPa. DE 695 33 513 T2 reports on the principle of separation of various so-called feedstocks, which may also consist of hydrocarbons, as can be found in natural gases. However, it is based on the separation principle of molecular diffusion (pFeed = PPermeat) or in other publications by means of per-evaporation. A separation by pressure-induced and non-diffusive preferred adsorption is not described.

DE 10 2004 001 974 A1 describes the possibility of Ofefinseparation under elevated pressure conditions. It describes the separation of close-boiling mixtures by molecular radii. Although feed-side pressures of 1 to 100 bar and a permeate-side pressure of 0.01 to 0 bar are reported here, the separation principle is the reverse of that of the invention, since the molecules of smaller diameters flow through the membrane and z. B. 1-butene is enriched in the permeate, while 2-butenes are retained. This separation method is unsuitable for the conditioning of natural gas and petroleum feed gases since most of the hydrocarbon mixture, namely methane, would have to pass through the membrane. That would be technically difficult to realize.

In patent DE 693 26 254 T2 it is described that it is possible to separate butane from methane by means of carrier-supported MFI membranes, although using a sweep gas on the permeate side and at practical pressures <5 bar is working. Also in the literature, the separation of natural gas components at 1 - 4 bar is described. Here and as with all other described separations of natural gas and Erdöibegleitgaskomponenten according to the adsorption method, the separation is carried out essentially by the so-called surface diffusion, which has so far deteriorated after increasing the feed pressure and the differential pressures between feed and permeate.

The zeolite membranes on porous supports can be prepared in various ways. Common is in situ crystallization directly on the support, or seed-based synthesis for more oriented, uniform growth.

Seed crystals are usually prepared and deposited separately for this purpose, see documents DE 10 2004 0001 974 A1 / DE 100 27 685 B4. Or a seed layer is produced directly on the support during a separate synthesis step, as described in patent DE 103 04 322A1. Subsequently, the formation of a continuous synthesis layer from a dilute solution out, the especially to support crystal growth. Both methods are very process-intensive.

Summary of the invention

The object of the invention is to provide a process for the separation of natural gas or Erdölbegleitgas components of inorganic porous membranes, in the higher hydrocarbons such as C ₃ and C ₄ of the lower hydrocarbon Ci from natural gas and Erdölbegleitgas effectively without costly relaxation and cooling using membrane technology The separation even on more advanced, inorganic porous membranes without the use of purge gases at elevated, practical pressure conditions and improved separation performance compared to low pressure applications and higher gas flow rate should be made.

Another object is to use smaller natural gas fields, since by means of membrane technology, a flexible, less complicated procedural method for removing higher hydrocarbons from the raw gas is available. Another object is to also find methods for removing higher hydrocarbons from the hitherto little or no use of associated petroleum gas or other hydrocarbon mixtures.

Another object is to provide an inorganic porous membrane with altered performance parameters.

The inventive method for separating natural gas or Erdölbegleitkomponenten of inorganic porous membranes is to supply in a separator gaseous natural gas or Erdölbegleitkomponenten with a pressure of greater than 5 bar the feed side of a supported inorganic porous membrane and dissipate a separated gas stream on the permeate side, wherein the pressure on the permeate side of the membrane is lower than on the feed side and adsorption and condensation of higher hydrocarbons to be separated C to C ₆ of Ci and in the pores of the membrane [8], and the temperature is less than 150 ° C, and wherein the membrane on the feed side has a microporous second separation layer which is arranged on a mesoporous first layer, and the first layer is arranged on a macroporous or mesoporous carrier, wherein the mesoporous first layer comprises particles of a ground zeolite having a particle size smaller than 1 μητι and the thickness of the mesoporous first layer less than 20 μιτι to less than 50 μιτι, and the thickness of the microporous second separation layer is 0.5 to 30 pm.

It has been found that with an increase in the feed pressure to 5 bar and constant or adjusted permeate pressures is always a reduction in the separation performance of the membranes in the potential use for the decomposition of natural gas and associated gas associated with the respective individual components. This justifies the more theoretical applications of inorganic membranes for the separation of natural gas and associated gas components. There was no evidence in the known methods for the separation by means of the layers produced under practical conditions at elevated pressure conditions.

The process according to the invention surprisingly results in pressure-mediated, intensified adsorption and condensation of the respective higher hydrocarbon from the hydrocarbon mixture present in the membranes used and in the pores of the membrane and by an applied pressure difference between feed and per - Meat for flow increase through the membrane. Thus, the separation of the respective higher hydrocarbon is favored according to the invention technically. This procedurally advantageous effect is only favorable at sufficiently high absolute pressures of the hydrocarbon mixture on the inorganic porous separating layer and by a specific membrane with the structure mentioned below. Pressure-mediated is defined as the improved segregation performance of the membrane due to the applied gas pressure of the feed compared to low-pressure applications. As practical pressures, pressures greater than 5 bar are defined, e.g. 6 - 200 bar, preferably 8 - 70 bar, in particular 10 - 30 bar. As low pressure defined pressures are less than 5 bar. The permeate defined is the gas flow passing through the membrane. The feed is defined as the gas flow to the membrane module input. The retentate is defined as the gas flow that does not pass through the membrane to the membrane module outlet.

This behavior can only be exploited on meso- and macroscopically dense membranes without leakage flow. The membranes required for this purpose were obtained with a prior art improved manufacturing method. The earth gas or petroleum feed gas or mixtures of natural gas or petroleum gas entraining components are pressurized to these inorganic porous membranes so that preferably the higher alkane adsorbs and condenses to the inorganic porous layer to a greater extent as low pressure applications and thereby separated from the feed becomes.

Particularly preferred materials of the inorganic porous layer, here called membrane, are densely grown Krästallite on the basis of zeolitic structure types, particularly preferably MFI, FAU, LTA, MOR, FER, MEL, BEA; ITR and KFI, preferably MF1 and FAU, and here particularly preferably the MFI structure with silicalite membranes without Ai content or MFI membranes with an aluminum content. Particularly preferred is the known ZSM-5 with öhb0 (0 <n <27). Particularly preferred in MFI membranes with aluminum proportions are Si / Al contents of greater than 75.

In general, the pore sizes in the range of the molecular diameters of the hydrocarbons to be separated are 0.3 to 2 nm, preferably 0.5 to 0.8 nm.

Also, amorphous inorganic membranes are preferred. Particularly preferred herein are silica membranes and carbon membranes having pore sizes in the range of 0.5-2 nm.

The membranes should be meso- and macroscopically dense and thus allow only adsorptive processes on the surface, whereby the mass transfer thus proceeds only through the intracrystalline pore system. Transport between the khstallites of the porous inorganic layer must not or only to a very small extent take place due to the applied pressures. Advantageous for the separation process are membranes which, due to their small layer thickness, permit high permeate fluxes. Therefore, the thickness of the separating layer is preferably less than 50 μιτι, e.g. 2-40 μηη, more preferably less than 30 μηη, e.g. 2 - 20 pm.

The separation of natural gas or Erdölbegleitgaskomponenten takes place in the simplest case by an applied feed pressure greater than 5 bar and a differential pressure between the feed and permeate side (Fig. 1, Example 1), preferably 4 - 10 bar. The feed pressure may deviate from optimum for the membrane process pressure conditions and by other technological processes, such as by the inlet pressure of the delivered raw gas. The permeate pressure sets in dependence on the permeate flow and can be lowered by pressure control to the corresponding pressure difference.

The pressure difference is preferably 1 to 30 bar, especially 4 to 20 bar and especially 4 to 10 bar. The temperature on both sides of the membrane is less than 150 ° C and is preferably in the range of - 40 to + 80 ° C.

A further development of the method further includes the selective separation by means of a modular, cascade separation plant, wherein preferably each of the highest hydrocarbon passes through the membrane and is separated from the feed. The retentate has over the input composition, the feed, a depleted in these components composition. The resulting retentate passes through another separation unit, which in turn separates the highest alkane contained in this mixture. This process is repeated until the original mixture of the natural gas or associated gas has been separated into its individual components.

The feed pressure in this process must always be in the area of the pressure-transmitting

Adsorption and condensation are. The highest alkane is defined as the hydrocarbon with the longest C-C carbon compound.

From the permeate can be done by compression or cooling, the separation of hydrocarbons. When the permeate is compressed, it is possible to recycle the remaining gaseous hydrocarbon mixture into the feed stream of the membrane reactor with the aim of using it as a whole.

The enrichment of the respective higher aikane and the associated preferred mass transport obviously takes place by increased adsorption and condensation of the higher hydrocarbons in the pores. This can be seen for example from a mixture of methane / n-butane with only 0.3% n-hexane. Here, n-hexane is first separated at the membrane at elevated pressures from the inorganic porous membrane, methane and n-butane remain in the retentate. If the n-hexane is separated off, the separation of n-butane is carried out in a subsequent separation step on a downstream membrane, as shown for example in FIG. 2 and in Examples 1 and 3. This effect is observed at elevated feed pressures of p _Feed > 5 bar. The process conditions and membrane geometry can be varied so that either individual hydrocarbons are selectively separated or incurred Kohienwasserstoffgemische in the permeate. The individual separation is shown, for example, in FIG. 2, where a plurality of membranes are arranged one behind the other and the separated hydrocarbon is removed after each membrane.

By applying high> 5 bar feed pressures, it is possible to use pressure differences between the feed and permeate sides without applying a vacuum to the permeate side. Thus, a general flux increase and thus permeate yields for technical applications are possible. With this method can also be dispensed with the use of sweep gas on the permeate side. There are several possibilities of permeate treatment available, in particular the compression. Depending on the overall technological process, the permeate can be recirculated uncompressed or compressed into the feed stream. The uncompacted recirculation makes sense if a compressor with subsequent condensate separation is already installed upstream of the membrane in the feed.

To ensure sufficient stability of the membrane, it is synthesized on a porous support. In addition to support materials made of metal composite membranes are mainly produced on corundum carriers, since they are cheaper to produce and membrane and support are similar in their chemical composition and their thermal expansion Verhaitenbehhaiten ago. Other carrier materials, such as porous glasses or porous metals, are also suitable.

Membranes with the required properties are easy to produce when the

Synthesis approach is simplified in that the difficult-to-produce seed layer is replaced by applying a ground slurry with the composition of the subsequent membrane layer. An MFi layer, for example, applied as a nucleation layer favors a uniform, secondary growth out of a synthesis solution. Also, this layer is a barrier layer, whereby the

Synthesis solution does not enter the porous Korundträger. Both lead to a reduction of the manufacturing costs, since interlayer (s) among other things of Ti0 _{2 are} not required and a complex seed coating omitted from the above publications. In addition, advantages of a technological nature result when using dilute synthesis solutions, for example a better flow through thinner layers.

Preferably, the material for the mesoporous layer is prepared by milling commercial zeolite material to a fineness <1 pm, preferably <500 nm. The advantage of ground particles consists in the very good gearing with the macroporous or mesoporous carrier material.

Generally, macroporous refers to pores with> 1000 nm, mesoporous pores with 2-50 nm and microporous pores with 0.1-2 nm.

The training e.g. a porous silicalite layer is preferably carried out by slip casting. The solids content! in the slip is preferably 0.5 to 10 wt .-%. For metal-supported membranes, electrophoretic deposition of the particles is also possible.

The mesoporous intermediate layer is heat treated to further enhance the adhesion and burnout of any organic suspending and binding agents, with a temperature below the phase transition of the silicalite being chosen. Preferably, the selected temperature of this temperature treatment is between 400 ° C and 800 ° C, more preferably between 500 and 700 ^D C.

The silicon / aluminum molar ratio of the synthesis solution for the secondary growth step (the formation of the microporous layer) is for e.g. MFI exemplifies> 2.5, preferably> 75. Higher proportions of aluminum result in a more hydrophilic behavior and are therefore disadvantageous for the separation of non-polar mixtures.

The composition of a silica synthesis solution can vary with respect to selectivity and flux, depending on the synthesis method, the reagents used, the physical synthesis parameters and the desired membrane properties. Possible synthesis compositions in the range of 100 mol Si0 ₂ : 0 - 35 mol SDA: 0 - 50 mol NaOH: 0 - 17 mol Al ₂ 0 ₃ and .000 - 100,000 mol H ₂ 0, where SDA for the structure-directing agents, also called template , stands. For example, SDA can be tripropylammonium hydroxide or tripropylammonium bromide or a mixture of both.

To realize technically relevant flows through the membrane, the synthesis composition, especially the template content and water content, is optimized (Example 2). Templat portions of from 0.01 to 1.2 mol and water contents of from 4,000 to 40,000 mol per 100 mol of SiO ₂ in the synthesis batch are preferred for increasing the fluxes. The pH of the synthesis solution is adjusted to 10 to 14, preferably between 1100 and 12.5, depending on the Si0 ₂ source used. Suitable silicon dioxide sources are dispersed SiO ₂ , tetraethyl orthosilicate (TEOS) and colloidal SiO ₂ , such as LUDOX or LEVASIL. The support provided with the mesoporous layer, eg of Siialtalt, is prepared prior to the synthesis in such a way that the synthesis solution only comes into contact with the membrane side. For this purpose, for example, in an inner coating tubular support the outside be sealed with Teflon tape or wax. In the case of external coating, sealing with Teflon caps can prevent access to the interior. The aim of the seal is to prevent zeolite growth on the desorption side. This results in an asymmetric structure of the carrier.

The synthesis can be carried out under autogenous pressure, under atmospheric pressure, standing or flowing, for 3 to 120 hours. Preferably, the synthesis is carried out under autogenous pressure at temperatures of 140 ° C to 200 ° C and 12 to 72 h, more preferably between 160 and 180 ° C and 16 to 48 h.

After synthesis, the supports with the synthesized membrane are rinsed in deionized water until unreacted synthetic components are removed from the pores. This is generally the case when the pH of the wash water, after repeated changes, is at a pH of 7.

The carriers are then gently dried. This can be done under room air conditions or after slow heating in a drying oven at 60 ° C. After drying, the removal of structure-directing templations takes place, since these are located in the zeolite pores and would thus prevent access of the gases to be separated. The calcination is carried out at a heating rate of 0.3 to 5.0 K / min, preferably at 1, 0 K / min at 400 to 550 C ° for 3 to 24 h, more preferably at 420 to 580 ° C for 5 to 12 h , carried out. Cooling is carried out at 0.1 - 5 K / min.

It has been found that the membranes produced by the above-mentioned process steps are extremely stable and are essentially pressure-stable for the process presented here. At low feed pressures and applied pressure differences between permeate and feed, only low leakage currents are measured (less than 0.1% of the total flow).

The invention will be explained in more detail by examples and drawings. Show in it

Fig. 1 Scheme of the method according to the invention

Fig. 2 Scheme of the method according to the invention in the form of a cascade of several separation membranes Fig. 3 Scheme of the process according to the invention with recycling of the retentate to the feed

4 shows a section through a membrane of the invention, scanning electronic recording,

Magnification 1000 times

5 as Fig. 4 with different composition (1000-fold magnification)

Examples

In Fig. 1, the feed 1, consisting essentially of a mixture of Ci-C ₄ hydrocarbons, introduced under a pressure P1 in a separation space. At the membrane 4 adsorption and condensation of C ₄ takes place. The permeate 3 in the form of C ₄ , which has passed through the membrane into the permeate space, is withdrawn as gas at the lower pressure P2. The depleted at C ₄ retentate 2 can be recycled or fed to another separation stage.

Further separators with retentates 2, 2 'and 2 "and the permeates 3, 3' and 3" are shown in Fig. 2, where k is the number of the module, and n represents the number of modules from k = 1 to k = n dar.

Fig. 3 shows the return of the permeate 3 'to the feed 1 and thus a new passage of the pre-separated gas mixture in the circulation.

4 shows an MFI separation layer (top) 14 after the composition of 100 moles of SiO ₂ : 0, 169 moles of Al ₂ O ₃ : 3.3 moles of TPABr: 3.3 moles of TPAOH: 3.3 moles of Na ₂ O. :

2,000 moles of H ₂ O, including MF layer of MFI 13, including corundum MF layer 12, including corundum support layer 1 1.

5 shows an MFI separating layer (top) 14 after the composition of 00 mol of SiO ₂ : 0, 169 mol of Al ₂ O ₃ : 0.6 mol of TPABr: 0.0 mol of TPAOH: 3.3 mol of Na ₂ O: 2,000 moles of H ₂ O, including MF layer of MFI 13, including corundum MF layer 12, including corundum support layer 11.

example 1

Pressure-mediated, enhanced adsorption of the higher hydrocarbon

The membranes are tested for their permeation behavior under different conditions. For this they are mounted in a stainless steel module, whereby a seal by means of O-rings takes place to Permeatraum. To perform permeation tests at various temperatures, the module was heated. According to an assignment Under practical conditions, there is always a lower pressure on the permeate side during the measurement than on the feed side (1.4 bar). The pressure on the feed side is adjusted to the test values by means of a back pressure regulator. The retentate flow is kept constant during the measurement by adjusting the feed flow to the permeate flow.

The results of the measurements are shown in the following tables.

Test 1 - Influence of differential pressure at constant permeate pressure

In this test it becomes obvious that the separation properties are dependent on differential pressure, feed flow and temperature. One recognizes an increase in the separation factor and the permeate content with an increase in the pressure difference between feed and permeate. The separation factor is defined as the quotient of the ratios of the components C ₄ to Ci in the permeate and retentate. Furthermore, the influence of the feed flow on the separation becomes clear as well as a temperature influence. (Table 1)

Test 2 - Influence of a higher alkane on the separation efficiency of methane / propane / n-butane and depletion of the higher alkane on the example of n-hexane.

If various alkanes are present in an alkane mixture in their condensation, the highest alkane is preferably first removed. In a mixture of methane / propane / n-butane / n-hexane, therefore, the n-hexane is preferably first separated off. The separation of the components methane / propane / n-butane is very low in this case, but can be carried out after separation of the higher alkane, here n-hexane, analogous to the separation 1 with higher separation factors. The separation factor is defined as the ratio of the concentrations of the higher alkane in the permeate to the retentate. (Table 2 and 3)

Testing 3

With this test, the influence of the pore size of different membranes on their separation performance becomes clear. With increasing pore size is compared to smaller pore sizes higher pressure for adsorption and especially condensation necessary to achieve a desired separation effect. While MFI membranes (pores = 0.53 × 0.56 nm) show the desired increased separation and permeation effect due to increased condensation and adsorption even at pressures above 6 bar, in the case of the FAU zeolite (pore = 0.74 nm ) and in the case of microporous silicon membranes (pores = 1 nm), the effect can be used only at significantly higher pressures. Advantageous for a river increase through the membrane with appropriate separation performance is therefore also increasing the pore size. (Table 4)

Table 1

Influence of the separation properties with increase of the feed pressure at constant maintained permeate pressure of 1, 4 bar

Table 2

Depletion of the higher alkane on the example of n-hexane; Permeate pressure 1, 4 bar

0.3 vol.% Hexane in a mixture of lower alkanes

hexane

Temp. Δρ V (Ret) V (Perm) Vo!.% L / h

^D C bar! / Hl / h Permeate Retentate Permeate Retentate

2 6 0.29 0.79 0.28 0.002 0.017

4 6 0.53 1, 34 0.21 0.007 0.012

25

6 6 0.87 1, 35 0.15 0.012 0.009

8 6 1, 29 1, 24 0.1 0.016 0.006

Table 3

Influence of a higher aikane (n-hexane) on the separation efficiency methane / propane / n-butane

Temp. Δρ V (Rel) V (pej-fn) V (Feed) Volume Percent Separation Factor Permeability

! n ° C bar l / hl / hl / h Feed Permeate Retentate Permeate / Retentate in l / (h * m ^{2 *} bar) c, c ₃ C ₄ Ci c ₃ c ₄ C, c ₃ C ₄ (C ₃ + C,) / C1

1 6 0.19 6.19 66.20 23.70 10.10 76.52 18.64 4.84 1.5 2.4 1.66 89

2 6 0.29 6.29 65.00 25.60 9.40 76.75 18.47 4.78 1.6 2.3 1.78 68

4 6 0.53 6.53 62.30 26.00 11.70 77.44 18.16 4.40 1.8 3.3 2.08 62

25 76.2 18.8 5.0

6 6 0.87 6.87 65.00 24.40 10.60 77.82 17.99 4.19 1.6 3.0 1.89 67

8 6 1,29 7,29 68,40 24,20 7,40 77,88 17,64 4,48 1,6 1,9 1,63 75

10 6 1,95 7,95 78,00 16,40 5,60 75,62 19,58 4,81 0,8 1,1 0,87 90

1 6 0.26 6.26 66.40 22.30 11.30 76.62 18.65 4.73 1.4 2.8 1.66 120

2 6 0.37 6.37 66.30 20.20 13.50 76.81 18.71 4.47 1.3 3.5 1.68 86

4 6 0.66 6.66 69.40 19.00 11.60 76.95 18.78 4.27

50 76.2 18.8 5.0 1.1 3.0 1.47 77

6 6 1.03 7.03 68.80 20.40 10.80 77.47 18.53 4.01 1.2 3.0 1.56 79

8 6 1.59 7.59 72.00 19.40 8.60 77.31 18.64 4.05 1.1 2.3 1.33 92

10 6 2.29 8.29 73.20 19.00 7.80 77.35 18.72 3.93 1.1 2.1 1.25 106

1 6 0.42 6,42 66,20 23,40 10,40 76,90 18,48 4,62 1,5 2,6 1,70 195

2 6 0,70 6,70 67,00 24,60 8,40 77,28 18,12 4,60 1,6 2,1 1,67 163

4 6 1,23 7,23 67,80 23,10 9,10 77,92 17,92 4,16 1,5 2,5 1,68 143

75 76.2 18.8 5.0

6 6 1,82 7,82 68,10 22,40 9,50 78,66 17,71 3,63 1,5 3,0 1,73 141

8 6 2.62 8.62 69.90 21.60 8.50 78.95 17.58 3.47 1.4 2.8 1.61 152

10 6 4,20 10,20 71,90 21,00 7,10 79,21 17,26 3,53 1,3 2,2 1,49 195

Table 4

Influence of the pore size of the separation membrane on separation parameters Separation factor and permeability, VFeed = 600 ml / min, T = 25 ° C

Example 2

Synthesis of the membrane unit

To produce the Siiikalithmembranen for gas separation, in particular for the separation of higher hydrocarbons of methane, Korundmonokanäle be used with an outer diameter of 10 mm, an inner diameter of 7 mm and a length of 125 mm. In addition, the carriers have a microfiltration layer of α-corundum provided by the manufacturer with an average pore size of 200 nm. The ends are sealed with glass solder.

For the mesoporous zeolite layer, a silicalite with a Si / Al

Molar ratio> 500 mitteis a stirred ball mill with deionized water as a dispersion medium without other additives to a fineness of dw-0.25, d ₅₀ = 0.43 and d ₉₀ = 0.80 pm ground. Mitteis a 5% suspension of the ground silicalite to which a binder is added, the corundum carriers are coated by slip casting. It forms after a service life of 5 min under the given conditions, a layer thickness of 25 pm.

Prior to the synthesis, the corundum support coated in the interior with milled silicalite crystals is heat-treated at 700 ° C. for 1 h. The synthesis solution to form a closed Fiims on the mesopo- Rösen Silikalithschicht has a composition of 100 mol of Si0 _2: 0.169 mole of Al ₂ 0 _3: 3.3 mol of TPABr: 3.3 mol TPAOH: 3.3 moles of Na ₂ O: 2.000 Mol H ₂ O, see FIG. 4. An average layer thickness of 40-75 pm is observed. The flow behavior of a membrane after this synthesis is 4.7 ml / min at a pressure difference on the feed and permeate side of 1 bar.

Another membrane with a closed, but thinner film, according to the synthesis approach of 100 moles of SiO ₂ : 0, 169 moles of Al ₂ O ₃ : 0.6 mol TPABr: 0.0 mol TPAOH: 3.3 moles of Na ₂ O: 2,000 Mol H ₂ O, see FIG. 5. An average layer thickness of 17-23 μm is observed. The flow behavior of a membrane after this synthesis is 18.5 ml / min at a pressure difference on the feed and permeate side of 1 bar.

As silicon source Levasil serves 300/30%, which contains a small amount of Al ₂ O ₃ . As a result, the Si / Al molar ratio is 300. TPABr is tetrapropylammonium bromide, TPAOH is tetrapropylammonium hydroxide. The water used is deionized water. Prior to the synthesis, the carriers are wrapped in fabric tape.

The hydrothermal synthesis is carried out in an autoclave at 180 ° C for 24 h. After synthesis, the Teflon tape is removed and the membranes are rinsed in deionized water. After a space drying of 3 days, the calcination was carried out at 450 ° C for 5 h.

Claims

claims

1. A method for separating natural gas or Erdölbegieitkomponenten inorganic porous membranes, characterized in that in a separator gaseous natural gas or Erdölbegleitkomponenten be supplied at a pressure of greater than 5 bar the feed side of a supported inorganic porous membrane and a separated gas stream on the Permeate side is discharged, wherein the pressure on the permeate side of the membrane is lower than on the feed side and an adsorption and condensation of separated higher hydrocarbons to C ₆ of Ci on and takes place in the pores of the membrane,

and the temperature is less than 150 ° C, and wherein the membrane on the feed side has a microporous second separation layer disposed on a mesoporous first layer and the first layer is disposed on a macroporous or mesoporous support, the mesoporous first layer Layer comprises particles of a ground zeolite having a particle size smaller than 1 pm, and the thickness of the mesoporous first layer is less than 20 μm to less than 50 μm, and the thickness of the microporous second separating layer is 0.5 to 30 μm.

2. The method of claim 1, wherein on cascaded membranes, a cascaded, staggered separation takes place from the highest to the lowest hydrocarbon successively from a non-membrane gas stream (retentate).

3. The method of claim 2, wherein the cascade consists of at least three sequentially connected membranes.

4. The method according to any one of claims 1-3, wherein as inorganic porous membranes zeolitic structures of the type MFl, FAU, LTA, MOR, FER, MEL, BEA, ITR or KFI, in particular MFl or FAU are used.

5. The method according to any one of claims 1-4, wherein the same type of zeolite structures are produced for the mesoporous first layer and for the microporous second layer, in particular MFI structures.

6. The method according to any one of claims 1-5, wherein the thickness of the mesoporous first layer is less than 50 μηη, in particular 20 - 30 pm.

7. The method according to any one of claims 1 to 6, wherein a membrane is used, the microporous layer has microchannels with pore sizes in the range of molecular diameter of the hydrocarbons to be separated from 0.3 to 2 nm, preferably in the range of 0.5-0 , 8 nm.

8. The method according to any one of claims 1 to 7, wherein inorganic membranes are used on a support material obtained by synthesis of zeolites on a mesoporous zeolite layer on the support, wherein zeolites of the same or similar composition as the zeolites of the release layer on a Partikei- size smaller than 1 μιη ground, applied 0.5 to 30 pm thick on the support and a temperature treatment at 400 - 800 ° C are subjected to the formation of a mesoporous structure, and the release layer on the mesoporous layer by hydrothermal treatment of an applied synthesis solution of Composition 100 mo! Si0 ₂ : 0 - 35 mol Tempiat: 0 - 50 mol NaOH: 0 - 17 mo! Al ₂ O ₃ : 1000 - 100,000 mol H ₂ 0 at pH 10 - 14 under autogenous pressure at 140 - 200 ° C for 3 - 120 hours is generated, and the layer thus produced is rinsed, dried and calcined.

9. A process according to claim 8, wherein inorganic membranes of silicalite having MFI structure are used.

10. The method according to any one of claims 1 to 9, wherein the Tempiatanteil 0.01 - 1.2 mo! and the water content is 4,000-40,000 moles per 100 moles of Si0 ₂ .

11. Inorganically porous membrane for the separation of natural gas or Erölbegleitkompo- components in the gas phase, consisting of a meso- or macroporous support, a mesoporous first associated layer of a Zeoiithmaterial containing particles from a milling process with a particle size less than 1 μιτι and a microporous second layer of a zeolite material bonded to the mesoporous layer, obtainable by a process in which (1) on a meso or macroporous support of metal or corundum, a mesoporous layer of a first zeolite material is prepared by milling the first zeolite material to a particle size <1pm to 10nm, entraining the ground first zeolite material and applying the slurry to the support; Heating the layer to a temperature below the phase transition temperature of the first zeolite material in the range of 400 to 800 ° C;

(2) the mesoporous layer according to step (1), a synthesis solution is applied, consisting of 00 mol of Si0 _2: 0 - 35 mol template: 0 - 50 moi NaOH: 0 - 17 moles of Al ₂ 0 _3: 1000-100000 moi H ₂ 0, wherein the Si / Al mole ratio is greater than 2.5, and heating the layer to 140 - 200 ° C for 3 to 120 hours at a pressure of 1 bar to autogenous pressure;

(3) the resulting membrane is washed with water until pH 7 is reached;

(4) the membrane is dried at room temperature to 60 ° C; and

(5) the membrane is calcined at 400 to 550 ° C for 3 to 24 hours at a heating rate of 0.5 to 5 K / min.

12. The method according to claim 1, characterized by the following features:

It is operated with feed pressures greater than 5 bar, the pressure on the permeate side is lower than on the feed side;

to increase the separation efficiency, a pressure-mediated, enhanced adsorption and condensation of the higher hydrocarbons at and in the pores of the membrane is used;

Meso- and macroscopically dense inorganic membranes with microchannels with pore sizes in the range of the hydrocarbons to be separated are used; the process temperature is chosen so as to ensure the pressure-mediated, enhanced adsorption and condensation of the higher hydrocarbons at and in the pores of the separation layer; and the temperature is less than 150 ° C.

13. The method of claim 12, wherein on sequentially connected membranes, the cascaded, staggered separation from the highest to the lowest hydrocarbon from the retentate.

14. The method of claim 12, wherein from the permeate by cooling or compression, the separation of hydrocarbons, and the remaining gaseous hydrocarbon mixture is recycled to the feed stream of the membrane reactor.

15. The method of claim 12, wherein inorganic membranes are used, which have been obtained by synthesis of zeolites on a mesoporous zeolite support layer, wherein zeolites of the same or similar composition as the zeolites of the support layer ground to a particle size smaller than 1 μηη, 0.5 to 30 μητι thick applied to the carrier layer and subjected to a hydrothermal treatment.

16. A process according to claim 12, wherein inorganic membranes of silicalite having MFI structure are used.

17. The method of claim 15, wherein the synthesis on the mesoporous layer with a synthesis solution of the composition 100 mol Si0 ₂ : 0 - 35 mol template: 0 - 50 mol NaOH: 0 - 17 mol Al ₂ 0 ₃ : 1000 - 100,000 mol H ₂ 0 takes place.

18. The process according to claim 17, wherein the template content is 0.01-1.2 mole and the water content is 4.000-40.000 mole per 100 moi Si0 ₂ content.

19. The method according to claim 18, where n is the pH of the synthesis solution pH 10 - pH 14, in particular pH 11 - pH 12.5.