Purification of lower olefins

Abstract

Disclosed herein are beds of materials and their use for removing contaminants, not limited to carbon monoxide, oxygen, carbon dioxide, acetylene, hydrogen, water, carbonyl sulfide, and hydrogen sulfide, from lower olefins, not limited to ethylene.

Description

Field of the Invention

[0001] Embodiments disclosed herein relate to the preparation and use of beds of materials and methods of purifying lower olefins including, but not limited to, ethylene, which may be used with feed stream purification using the materials in a single packed bed for olefin purification.

[0002] background

[0003] Many products are made of polymer materials. An example is polyethylene (PE). PE is produced in various forms, including as high density polyethylene (HDPE). However, the ethylene monomer units that form PE in its various forms must be purified to remove pollutants. In fact, the polymer industry tends to be more stringent about the requirements of monomer purity. This trend is related to the higher need to remove trace or even ultra-trace levels of pollutants from monomer streams before polymerization. Considering the high sensitivity to certain pollutants, acceptable impurity levels have been reduced to low ppb levels from ppm / ppb levels in some polymerization processes. For example, metallocene catalysts show high sensitivity, and there are usually many impurities, even if these impurities are low and variable concentrations, they may also have a negative impact on the yield and effective production of various products such as polyethylene.

[0004] Particularly for the PE industry, common ethylene poisons for metallocene catalyst types include: CO, CO2, O2, acetylene, H2, H2O, sulfur compounds such as carbonyl sulfide (COS), hydrogen sulfide (H2S), CH2SH, oxygen-containing compounds and nitrogen-containing compounds, etc. The presence of these elements at ppm levels tends to block catalyst active sites and reduce the productivity and overall yield of PE manufacturing. In order to enhance the catalytic productivity of PE polymerization units, the ethylene feedstock (ethylene monomer) is conventionally purified before the polymerization reaction.

[0005] Conventionally, multiple beds with specific catalysts or absorbents are used to remove individual pollutants in a sequential manner under different process conditions. This approach requires significantly higher capital and operating costs and processing time. However, advantageously, arranging the material of the present invention on a single bed enables the removal of all pollutants under one process condition, thereby overcoming the above limitations.

[0006] Thus, the material beds and purification methods that can be provided in various forms and alternative forms according to embodiments of the present invention reduce the number of steps required for olefin purification. Depending on the need, these may be used as part of a purification system using a single large reactor.

[0007] Implementation Plan Overview

[0008] According to various embodiments and alternatives, it will be understood that the materials disclosed herein and their production methods are suitable for removing a wide range of pollutants, including the types of polluting compounds mentioned herein, to ppb levels. Such a bed of material can be periodically regenerated and reused within multiple cycles. By way of illustration and not limitation, exemplary embodiments related to the present disclosure include a bed of a material composition comprising a copper catalyst with optional one or more promoters and a carrier, and a porous inorganic oxide carrier. In some embodiments, these materials are placed in a single bed. In addition to other uses, the material bed thus formed according to various embodiments and alternatives can be used for ethylene purification. These materials can be used to remove impurities in ethylene monomer units or other products moving as feed in a gaseous stream in an environment (e.g., a large reactor) at a temperature range of about 40°C to 120°C for about 1,000 to about 10,000 h. -1 An exemplary feed flow rate range of 1000 psig and 2000 psig is provided, and during use, the feed may be operated at an exemplary pressure of about 1-1,000 psig. Depending on the requirements, the operating conditions may be at a temperature of about 10-70° C., more particularly 20-50° C., and a pressure of about 5-50 bar as the feed passes through the bed of material.

[0009] As disclosed herein, such materials (e.g., material beds) according to embodiments of the present invention and alternatives are suitable for removing impurities from feed streams. Examples of such feeds are ethylene monomers traveling through reactors, or streams of propylene or butene monomers (as non-limiting examples). Carbon monoxide (CO) is a type of such impurity. CO can be removed alone, or it can be removed simultaneously with the removal of other compounds, which include but are not limited to oxygen (O ), carbon dioxide (CO ), alkynes / acetylene, hydrogen (H ), water, carbonyl sulfide, hydrogen sulfide, and oxygen-containing compounds. Therefore, the materials (e.g., material beds) of embodiments of the present invention can be more effective than conventional multi-bed systems. In addition, they reduce the time and cost (as an example) required for PE production, reduce other possible capital costs, and provide other purposes requiring gaseous stream purification.

[0010] Various implementations and alternatives

[0011] In some embodiments, the material of the present disclosure (e.g., arranged as a material bed) comprises a copper catalyst with one or more optional promoters and carriers, and a porous inorganic oxide. In other embodiments, the promoter is selected from Fe, Ni, Zn, La, Ce, Zr, Mg, Mn, Pd, Pt (to include compounds containing these elements) and combinations thereof. In yet other embodiments, the carrier is selected from activated carbon, carbon nanotubes, alumina, modified alumina, silica, zeolite, zirconium oxide, cerium dioxide. In some embodiments, the material includes one or more porous inorganic materials comprising alumina, zeolite, clay and combinations thereof. According to the embodiments of the present disclosure, including but not limited to materials comprising zeolites selected from naturally occurring or synthetically manufactured materials, and clays selected from sodium bentonite or layered double hydroxide clays.

[0012] In some embodiments, the formation of the material in the bed includes mechanical mixing of the different components, followed by extrusion and drying. Optionally, the material is granulated after drying. In some embodiments, these materials are subjected to reduction using a stream comprising H2 and optional additional gases such as methane, N2. Example

[0013] Example 1 - Production of CuOZnO

[0014] CuOZnO composite material is synthesized by coprecipitation. According to a known method, a mixed metal nitrate solution is prepared so that the Cu nitrate concentration of the solution is 40g / L and the Zn nitrate concentration is 80g / L. Then 170g / L of sodium carbonate solution is used to coprecipitate with the solution, keeping the pH between 6 and 8 units, and then aging the precursor material for 2 hours under stirring until a cake is formed. The cake is then filtered and washed in a filter press until the conductivity measured is less than 50 micro-Siemens (microsiemen). The washed cake is spray dried to produce CuOZnO powder, which is then calcined for 4 hours at 450°C in a rotary calciner.

[0015] Example 2 - Production of Material Bed

[0016] The material was produced by mixing 75 g of activated alumina, 5 g of sodium-containing bentonite clay and 20 g of CuOZnO (catalyst, Cu / Zn weight ratio of 1 to 2) powders by weight. The granulometry of the powders was less than 100 mesh. The mixing was done by using a kneading mixer. After complete homogenization of the raw materials by adding 150 ml of water, the material was extruded into a size of 6 mm x 3 mm and dried at 85°C for 12 h.

[0017] Embodiment 3-6

[0018] The following examples (Examples 3-6) in Table 1 list the weight percentages of a set of exemplary materials formed by the process steps listed in Example 2, except for one example. However, Example 6 was formed from uncalcined CuOZnO powder, which was extruded and dried at 85°C, and then calcined at 600°C for one hour:

[0019] Table 1

[0020]

[0021] Embodiment 7-9

[0022] The following examples (Examples 7-9) in Table 2 list the weight percentages of the various component materials, which are generally made by the process steps listed in Example 2:

[0023] Table 2

[0024]

[0025] Example 10 - Implementation of CuFeCe Co-precipitation

[0026] CuOZnO was prepared by coprecipitation following the procedure described for CuOZnO in Example 1. x , except that the nitrate solution had a concentration of 55 g / L for Cu, 300 g / L for Fe and 15 g / L for Ce. x , and then forming a product according to the procedure of Example 2, and the product contains the weight percentages listed in Table 2 above for Example 10.

[0027] Example 11 - Use of Material Bed for Ethylene Purification

[0028] In these tests, each bed material was crushed to a size of 1.2 to 1.4 mm. On the one hand, the bed materials of Examples 1-10 were reduced in situ at 200°C for 12 hours using 10% H2 in N2, and then in situ reduced for 2 hours using 99.99% H2, after which the materials were subjected to an impurity removal experiment. Examples 2-10 were tested for CO removal and simultaneous removal of oxygen, acetylene, and hydrogen (collectively referred to as simultaneous contaminant removal). A fixed bed reactor was loaded with 15 mL of crushed bed material according to an embodiment of the present invention, thereby maintaining a D / Dp ratio (particle diameter / reactor diameter) greater than 10. The bed was further prepared as needed, and before the feed was passed through the bed, the bed material could be passed through a reducing gas stream comprising hydrogen, nitrogen, and methane at a temperature of 100-400°C, wherein the copper was in a substantially reduced form. At 1,000-10,000 h -1The GSHV ranges from 40°C to 100°C for each run as discussed below, and the test runs are at least ten hours at each temperature condition. Optionally, the GSHV can be run for 1000-5000h -1 Ethylene gas (i.e., the monomer to be subsequently converted into polyethylene) containing 10 ppm of CO (one of the exemplary contaminants or impurities) was fed to the reactor at 25 bar(g). For experiments involving simultaneous contaminant removal, a commercially available ethylene gas mixture contaminated with 10 ppm CO, 20 ppm O2, 10 ppm acetylene, and 80 ppm H2 was used.

[0029] Regarding Examples 2-6, at a temperature of 40°C and 3,000 h -1 GHSV, test results show >99% removal of CO and >99% removal of pollutants after at least 30 hours of operation. In the temperature range of 80℃-100℃, test results show >99% removal of CO and >99% removal of pollutants after at least 30 hours of operation.

[0030] Regarding Examples 7-10, at a temperature of 40°C and 1,000 h -1 The GHSV of 1.5 GHSV was 2.5 GHSV, and the test results showed >99% removal of CO and >99% removal of pollutants after at least 30 hours of operation. In the temperature range of 80℃-100℃, the test results showed >99% removal of CO and >99% removal of pollutants after at least 24 hours of operation.

[0031] As described previously, Example 1 provides a comparative example using CuOZnO synthesized by a previously known coprecipitation technique. -1 GHSV, test results show >99% removal of CO and >99% removal of pollutants after at least 30 hours of operation. -1 -3,000h -1 The GHSV range of the test results showed that after running for at least 24 hours, >99% of CO was removed and >99% of pollutants were removed at the same time. In addition, Example 1 resulted in a GHSV range of >99% of CO was removed and >99% of pollutants were removed at the same time after running for at least 24 hours. -1 When the GHSV feed through the reactor is at a level of CO2 greater than >10 ppmv (parts per million by volume), it is often necessary to have additional beds to remove CO2 and H2O (if present).

[0032] Thus, Examples 2-10 illustrate formation methods and a set of bed materials obtained by practicing such methods, all in accordance with embodiments of the present invention. For these examples, the bed materials were found to remove >99% of all CO from a gaseous stream. Likewise, they were found to remove all major pollutants simultaneously from concentrations in the ppm range to ppb levels (much less than 0.1 ppm).

[0033] The results in Examples 2-10 are comparable to those of the practice of Example 1 (Comparative Example), but the former are associated with fewer manufacturing steps and therefore reduced time, and reduced costs compared to conventional practices such as Example 1, which also require additional beds (one or more) typically with molecular sieves to remove CO and H2O. While Examples 2-10 are provided, many other variations and alternatives are included within the scope of the various embodiments and alternatives provided and contemplated herein.

[0034] It will be understood that the embodiments described herein are not limited to their application to the details of the listed teachings and descriptions. On the contrary, it will be understood that the embodiments of the present invention and alternatives as described and claimed herein can be practiced or performed in various ways. In addition, it should be understood that the words and phrases used herein are for descriptive purposes and should not be considered restrictive. Such words and phrases such as "including", "for example", "comprising", "such as", "containing" or "having" and variations of these words are used herein to include the terms listed thereafter, and the equivalents of these terms, and additional terms.

[0035] Therefore, the foregoing description of embodiments and alternatives is intended to illustrate rather than to serve as a limitation on what scope is disclosed herein. The description herein is not intended to limit the understanding of the embodiments to the precise form disclosed. Those of ordinary skill in the art will appreciate that modifications and variations of these embodiments are reasonably possible in view of the above teachings and descriptions.

[0036] The following claims are representative and are not intended to limit the scope of claimed subject matter in a future application claiming the benefit of this application.

Claims

1. A method for purifying lower olefins of impurities or contaminants comprising passing a feed through a single bed of material comprising copper, at least one promoter, at least one support, and at least one porous inorganic oxide, wherein the lower olefin is selected from ethylene, propylene and butene, wherein the formation of the material in the bed comprises mechanical mixing of the components followed by extrusion and drying, Therein the material is reduced at a temperature of 100-400°C using a reducing gas stream comprising hydrogen, nitrogen and methane before the feed is passed through a bed of material.

2. The method of claim 1, wherein the promoter is selected from the group consisting of Fe, Ni, Zn, La, Ce, Zr, Mg, Mn, Pd, Pt, Ru and Rh and combinations thereof.

3. The method according to claim 1, wherein the carrier is selected from activated carbon, carbon nanotubes, alumina, modified alumina, silica, zeolite, zirconium oxide, ceria.

4. The method of claim 1, wherein the porous inorganic oxide comprises at least one of alumina, zeolite and clay, and combinations thereof.

5. The method of claim 1, wherein the contaminant comprises at least one of CO, H2, C2 or C3 acetylenes, H2O, CO2, H2S, methanol, arsenic, and phosphine.

6. The method of claim 1 resulting in the removal of each contaminant to a level of less than 0.1 ppm.

7. The process according to claim 1, wherein the feed is passed through the bed at a temperature of 10-70°C and at a pressure of 5-50 bar.

8. The method according to claim 7, wherein the temperature is 20-50°C.

9. The process according to claim 1, wherein the bed is heated to a temperature of 100-400°C for 1-24 hours under an inert gas stream comprising nitrogen and methane.

10. A method according to claim 9, wherein the copper is substantially in reduced form.

11. The method of claim 1, wherein the concentration of copper is no greater than 50 wt%.

12. The method of claim 1, wherein the concentration of copper is no greater than 20 wt%.

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