PURIFICATION OF LOWER OLEFINS

Abstract

Disclosed herein are a bed of materials and use of it for removing contaminants not limiting to carbon monoxide, oxygen, carbon dioxide, acetylene, hydrogen, water, carbonyl sulfide and hydrogen sulfide from lower olefins without limiting ethylene.

Claims

1. A process for the purification of impurities or contaminants of lower olefins comprising passing a feed over a bed of material, the material comprising copper, one or more promoters and supports, and porous inorganic oxides.

2. The process of claim 1, wherein the promoters are selected from Fe, Ni, Zn, La, Ce, Zr, Mg, Mn Pd, Pt, Ru, and Rh.

3. The process of claim 1, wherein the support is selected from activated carbon, carbon nanotube, alumina, modified alumina, silica, zeolites, zirconia, ceria.

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

5. The process of claim 1, wherein the contaminants comprise at least one of CO, H.sub.2, C2 or C3 acetylene, H.sub.2O, CO.sub.2, H.sub.2S, methanol, arsine, and phosphine.

6. The process of claim 1, resulting in removal of each contaminant below a level of 0.1 ppm.

7. The process of claim 1, wherein prior to passing the feed over the bed, the bed material is reduced with a reducing gas steam comprising hydrogen, nitrogen, and methane at a temperature of 100-400 C.

8. The process of claim 1, wherein the feed is passed over the bed at a temperature between about 10-70 C., and at a pressure in a range of about 5-50 bar.

9. The process of claim 8, wherein the temperature is between 20-50 C.

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

11. The process of claim 10, wherein prior to passing the feed over the bed, the bed material is passed through a reducing gas steam comprising hydrogen, nitrogen, and methane at a temperature of 100-400 C., wherein the copper is substantially in reduced form.

12. The process of claim 1, wherein the lower olefins are chosen from ethylene, and propylene, and butylene.

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

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

Description

EXAMPLES

Example 1Production of CuOZnO

[0010] CuOZnO composites are synthesized by coprecipitation. According to one such known method, a mixed metal nitrate solution was prepared having a concentration of 40 g/L for Cu nitrate and 80 g/L for Zn nitrate. The solution was then coprecipitated with 170 g/L of a sodium carbonate solution, keeping the pH between 6 to 8 units, and this precursor material was then aged under stirring for 2 hours until a cake was formed. The cake was then filtered in a filter press and washed until electrical conductivity measured less than 50 microsiemens. The washed cake was spray dried to generate a CuOZnO powder, then calcined at 450 C. for 4 hours in a rotary calciner.

Example 2Production of a Bed of Material

[0011] A material was produced by mixing powder by weight of 75 g of activated alumina, g of sodic bentonite clay and 20 g of CuOZnO (catalyst, Cu/Zn weight ratio of 1 to 2). Granulometry of the powder was less than 100 mesh. Mixing was accomplished by using a kneader mixer. After complete homogenization of the starting materials was achieved by adding 150 ml of water, the material was extruded to a size of 6 mm3 mm and dried at 85 C. for 12 h.

Examples 3-6

[0012] The following examples in Table 1 (Examples 3-6) set forth weight percentages of a group of exemplary materials, which, except for one of the examples, were formed by the process steps set forth in Example 2. However, Example 6 was formed from uncalcined CuOZnO powder, which was extruded and dried at 85 C., followed by calcination at 600 C. for one hour:

TABLE-US-00001 TABLE 1 Example 3 Example 4 Example 5 Example 6 activated alumina 58% 50% 75% CuOZnO 40% 50% 19.94% 100 CuFeCe sodic bentonite clay 2% 5% promoter 0.06% (Pd or Pt)

Examples 7-9

[0013] The following examples in Table 2 (Examples 7-9) set forth weight percentages of different component materials, generally made by the process steps set forth in Example 2:

TABLE-US-00002 TABLE 2 Example 7 Example 8 Example 9 Example 10 activated alumina 75% 50% 38% 75% CuZn adsorber 19.9% 5% 20% CuFeCe adsorber 20% sodic bentonite clay 5% 5% 5% 5% promoter 0.1% (NiO, Ag.sub.2O or La.sub.2O.sub.3) zeolite 13X 40% 37%

Example 10an Embodiment for Coprecipitation of CuFeCe

[0014] A CuOZnO.sub.x was prepared by coprecipitation in accordance with the procedure in Example 1, described for a CuOZnO, except nitrates solutions were in the concentration of 55 g/L for Cu, 300 g/L for Fe and 15 g/L for Ce. Using the CuOZnO.sub.x formed in this manner, a product was then formed in accordance with the procedures of Example 2, and containing the weight percentages set forth in Table 2, above, for Example 10.

Example 11Use of Bed of Materials for Ethylene Purification

[0015] In these tests, the respective bed material was crushed to a size of 1.2 to 1.4 mm. In one aspect, the bed materials of Examples 1-10 were reduced in situ using 10% H.sub.2 in N.sub.2 at 200 C. for 12 hours, then using 99.99% H.sub.2 for 2 hours before subjecting the materials for impurity removal experiments. Examples 2-10 were tested for removal of CO and simultaneous removal of oxygen, acetylene and hydrogen (referred to collectively as simultaneous contaminants removal). A fixed bed reactor was loaded with 15 mL of crushed bed materials according to the present embodiments, maintaining a D/Dp ratio (particle diameter per reactor diameter) greater than 10. As desired to further prepare the bed, prior to passing the feed over the bed, the bed material may be passed through a reducing gas steam comprising hydrogen, nitrogen, and methane at a temperature of 100-400 C., with the copper in substantially reduced form. Each of the runs was conducted at a GSHV range from 1,000 to 10,000 h.sup.1, varying the temperature from 40 C. to 100 C. as discussed below, and the tests were run for at least ten hours at each temperature condition. Optionally, the GSHV could be run at 1000-5000 h.sup.1. An ethylene gas (i.e., monomer to be converted later into polyethylene) comprised of 10 ppm of CO (one of the exemplary contaminants or impurities) fed the reactor at 25 bar(g). For experiments directed to simultaneous contaminants removal, a commercial ethylene gas mixture contaminated with 10 ppm CO, 20 ppm O.sub.2, 10 ppm acetylene and 80 ppm H.sub.2 was used.

[0016] With regard to Examples 2-6, at a temperature of 40 C. and GHSV of 3,000 h.sup.1, results of testing showed >99% removal of CO as well as simultaneous removal of >99% of contaminants after at least 30 hours on stream. At a temperature range from 80 C. to 100 C., results of testing showed >99% removal of CO as well as simultaneous removal of >99% of contaminants after at least 30 hours on stream.

[0017] With regard to Examples 7-10, at a temperature of 40 C. and GHSV of 1,000 h.sup.1, results of testing showed >99% removal of CO as well as simultaneous removal of >99% of contaminants after at least 30 hours on stream. At a temperature range from 80 C. to 100 C., results of testing showed >99% removal of CO as well as simultaneous removal of >99% of contaminants after at least 24 hours on stream.

[0018] As previously described, Example 1 provides a comparative example utilizing a CuOZnO synthesized by previously known coprecipitation techniques. At a temperature of 40 C. GHSV of 1,000 h.sup.1, results of testing showed >99% removal of CO as well as simultaneous removal of >99% of contaminants after at least 30 hours on stream. At a temperature range from C. to 100 C. and GHSV range from 1,000 h.sup.1 to 3,000 h.sup.1, results of testing showed >99% removal of CO as well as simultaneous removal of >99% of contaminants after at least 24 hours on stream. In addition, Example 1 resulted in CO.sub.2 at levels greater than >10 ppmv (part per million by volume) when fed through the reactor at a temperature of 40 C. at a GHSV of 3,000 h.sup.1 wherein usually one needs to have additional beds to remove CO.sub.2 and H.sub.2O if any.

[0019] Accordingly, Examples 2-10 are illustrative of a method of forming, and a group of bed materials obtained by the practice of such methods, all in accordance with present embodiments. For these examples, the bed materials were found to remove >99% of all CO from the gaseous streams. Likewise, they were found to simultaneously remove all major contaminants from a concentration in the ppm range to ppb levels (much less than 0.1 ppm).

[0020] The results in Examples 2-10 are comparable with the results from the practice of Example 1 (comparative example), but the former are associated with fewer manufacturing steps, and thus reduced time, and reduced cost compared to conventional practices such as Example 1, which also requires additional bed(s) usually with molecular sieves to remove CO and H.sub.2O. While Examples 2-10 are provided, many other variations and alternatives are included within the scope of multiple embodiments and alternatives provided for and contemplated herein.

[0021] It will be understood that the embodiments described herein are not limited in their application to the details of the teachings and descriptions set forth. Rather, it will be understood that the present embodiments and alternatives, as described and claimed herein, are capable of being practiced or carried out in various ways. Also, it is to be understood that words and phrases used herein are for the purpose of description and should not be regarded as limiting. The use herein of such words and phrases as including, such as, comprising, e.g., containing, or having and variations of those words is meant to encompass the items listed thereafter, and equivalents of those, as well as additional items.

[0022] Accordingly, the foregoing descriptions of embodiments and alternatives are meant to illustrate, rather than to serve as limits on the scope of what has been disclosed herein. The descriptions herein are not meant to limit the understanding of the embodiments to the precise forms disclosed. It will be understood by those having ordinary skill in the art that modifications and variations of these embodiments are reasonably possible in light of the above teachings and descriptions.