A method for preparing an oxygen carrier for ethane chemical chain production of ethylene and its application

Abstract

The present invention discloses the modification and application of an oxygen carrier for ethane chemical chaining to ethylene technology. The oxygen carrier is a NiO / MgO oxygen carrier. By adding the additive Fe2O3, the C2H6 conversion rate and C2H4 selectivity in the fuel reactor can be improved. The oxygen carrier is prepared by a coprecipitation method. The oxygen carrier is used in ethane chemical chaining to ethylene technology, wherein the reaction temperature in the fuel reactor is 600-1000°C, the reaction temperature in the air reactor is 600-1000°C, and the reaction pressure is 0.1-1 MPa. The oxygen carrier preparation method uses nickel nitrate, iron nitrate, and magnesium nitrate as precursors and an alkaline solution as a precipitant. After precipitation, the oxygen carrier is filtered, washed, dried, and calcined to obtain the oxygen carrier NiO-Fe2O3 / MgO.

Description

Technical Field

[0001] The invention relates to the modification and application of an oxygen carrier in the ethane chemical chain production of ethylene technology, belonging to the oxygen carrier technology in the field of ethane chemical chain production of ethylene. Background Art

[0002] The ethylene industry is a leading sector in the petrochemical industry, accounting for over 75% of petrochemical output and occupying a crucial position in the national economy. Ethylene production is now considered a key indicator of a country's petrochemical development. China and the United States, two major petrochemical producers and consumers, are leading the rapid growth of global ethylene production capacity. China surpassed the United States in 2022 to become the world's largest ethylene producer. Global oil product demand growth is expected to slow, while demand for chemical products will steadily increase. Investment in the ethylene industry is expected to maintain steady growth. Ethylene feedstocks are becoming more diversified and lightweight, plants are becoming larger, and production processes and technologies are becoming more diverse and low-carbon. This is widening regional disparities in ethylene industry development and intensifying competition. By the end of 2021, my country had 61 ethylene production companies with 79 operational ethylene plants, totaling 41.68 million tons / year, accounting for approximately 18% of the global total. These include 41 steam cracking ethylene plants with a production capacity of 29.48 million tons / year; 27 coal / methanol to olefins plants with a production capacity of 7.15 million tons / year; and 6 ethane cracking ethylene plants with a production capacity of 4.9 million tons / year.

[0003] In recent years, researchers have conducted extensive research in areas such as the utilization of inexpensive raw materials, catalyst innovation, and the development of low-energy, short-process technologies. They have explored various new ethylene production technologies and achieved significant progress. Methane oxidative coupling to ethylene suffers from high reaction temperatures, high heat release, and high investment costs. Direct ethane oxidative dehydrogenation to ethylene requires large amounts of inert gas to dilute the reaction mixture away from flammable areas, increasing safety risks and significantly increasing equipment investment and operating costs. While ethane CO2 oxidative dehydrogenation to ethylene avoids the use of large amounts of inert gas, it also faces practical challenges. On the one hand, CO2 conversion is typically low due to the limitations of the reverse water-gas reaction equilibrium, and the large amount of carbon monoxide generated in this process increases downstream separation costs. On the other hand, the high endothermicity of the reaction also increases operating costs. Direct ethylene production from synthesis gas has completed pilot testing and achieved significant results. However, further research and development is needed to better balance catalyst performance and process operating conditions. Furthermore, the research and development of high-efficiency reactors and supporting engineering technologies are key to its industrial application.

[0004] Chemical looping technology is a process intensification technology. The chemical looping of ethane to ethylene utilizes the lattice oxygen of metal oxide-based oxygen carriers to promote the conversion of ethane. Since the reaction process does not require oxygen and inert gas dilution, it greatly improves the safety environment of the reaction process and reduces the process investment and operating costs. The process consists of two steps: first, ethane is oxidized by the oxygen carrier to produce ethylene and water, and the oxygen carrier is reduced by ethane; then, air is introduced to oxidize the oxygen carrier and release heat to complete a cycle. Usually, the oxygen carrier in this technology undergoes multiple redox cycles. This technology has the characteristics of low oxygen carrier price, self-heating continuous operation of the process, and breaking the thermodynamic equilibrium of alkane dehydrogenation. It can greatly increase the yield of olefins, and the process flow is short, saving investment and operating costs, so it has good development and application prospects. At present, this technology has not been applied industrially. The main reason is that the oxygen carrier still has problems with low activity, poor selectivity and stability. Elvadawi AH et al. investigated a series of VO in a circulating fluidized bed reactor. x -MoOx / γ-Al2O3 oxygen carrier can still obtain 55%-85% ethylene selectivity after multiple reaction-regeneration cycles in the temperature range of 500-650℃, but the ethane conversion rate is relatively low. Khadzhiev SN et al. tested a series of VO loaded on γ-Al2O3 x and MoO x Oxygen carrier, it was found that MoO x The ethane conversion rate on the Al2O3 oxygen carrier was 66.5%, and the ethylene selectivity was 94.5%. During the ethane chemical chaining process to ethylene, the oxygen carrier is in a constant state of oxygen release and absorption, so the oxygen carrier's oxygen release and absorption capacity is extremely important. Nickel oxide and iron oxide are commonly used active components in catalysis, with nickel oxide being particularly active and frequently used in hydrocarbon oxidation. When using ethane as fuel, the oxidation products can range from C2H4 and H2 to CH4, CO2, and CO, making improving C2H4 selectivity crucial. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides an oxygen carrier for ethane chemical chain to ethylene technology with a simple modification method, high activity and high C2H4 selectivity, as well as its preparation method and application.

[0006] The oxygen carrier of the ethane chemical chain technology for producing ethylene is a NiO / MgO-based oxygen carrier, which is modified to obtain a NiO-Fe2O3 / MgO-based oxygen carrier.

[0007] The oxygen carrier of the present invention is used in the ethane chemical chain to ethylene technology, wherein the reaction temperature in the fuel reactor is 600-1000°C, the reaction temperature in the air reactor is 600-1000°C, and the reaction pressure is 0.1-1MPa.

[0008] The oxygen carrier is in the form of microspheres, with a particle size generally ranging from 10 μm to 700 μm, preferably from 50 μm to 500 μm. Other suitable inorganic refractory components, such as one or more of aluminum oxide, titanium oxide, and silicon oxide, may be added during use.

[0009] The oxygen carrier of the present invention is prepared by a co-precipitation method. The specific process is as follows: nickel nitrate, iron nitrate, and magnesium nitrate are used as precursors, and an alkaline solution is used as a precipitant. After precipitation, the sample NiO-Fe2O3 / MgO is obtained through filtration, washing, drying, and roasting.

[0010] In the oxygen carrier preparation method of the present invention, the Fe2O3 mass content in the oxygen carrier is 0-20%, the alkaline solution can be sodium hydroxide, ammonia water, sodium carbonate, etc., the pH value during precipitation is 9-11, the aging temperature is room temperature to 80°C, the aging time is 2-72 hours, the number of distilled water washing times is 2-6 times, the drying time is 1-36 hours, and the calcination is performed at 400-1000°C for 2-15 hours.

[0011] Compared with the prior art, the oxygen carrier of the ethane chemical chain to ethylene technology of the present invention has the advantages of simple modification method, high activity and high C2H4 selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a temperature-programmed reduction diagram of the NiO-Fe2O3 / MgO oxygen carrier prepared in an embodiment of the present invention. DETAILED DESCRIPTION

[0013] The process and effects of the method of the present invention are further illustrated below with reference to the following examples. In the modification process of the oxygen carrier for the ethane chemical chaining to ethylene of the present invention, the Fe2O3 mass content, the precipitant, and the pH value are important factors.

[0014] Example 1

[0015] Take a certain amount of Ni(NO3)2·6H2O and Mg(NO3)2·6H2O and mix them with distilled water to a concentration of 1 mol·L -1 Take 1.6g Fe(NO3)3·9H2O and distill it into a solution with a concentration of 1mol·L -1 The solution was co-precipitated with sodium hydroxide as a precipitant, the pH value was controlled at about 10, the aging temperature was 40°C, the aging time was 24 hours, and then the mixture was filtered, the filter cake was washed 3 times with distilled water, dried in a drying oven at 120°C overnight, and calcined in a muffle furnace at 900°C for 4 hours to obtain NiO-Fe2O3 / MgO, wherein the Fe2O3 mass content was 10% and the NiO mass content was 10%.

[0016] The performance evaluation of the oxygen carriers prepared in the above-mentioned embodiments and comparative examples was conducted as follows. The oxygen carriers prepared above were sieved, and 0.4 g of oxygen carriers with a particle size of 40-60 mesh were taken for performance testing in a fixed-bed quartz tube reactor. The quartz tube was φ8×2, and the feed gas composition was: 10% C2H6, 90% N2. Under nitrogen protection, the sample was heated from room temperature to 650°C, and then the feed gas was introduced for reaction at a feed gas flow rate of 50 ml / L. After reacting for 1-5 minutes, nitrogen was introduced for 10 minutes, and then air was switched to oxidation at a flow rate of 30 ml / L. After 10 minutes, nitrogen was introduced for purging, completing an oxidation-reduction cycle. Gas chromatography was used for online analysis, TCD detection, a 5A molecular sieve column, and a Porapak Q column. The C2H6 conversion rate was 95%, and the C2H4 selectivity was 75%.

[0017] Example 2

[0018] Following the preparation steps of Example 1, except for a 5% Fe(NO₃)₃·9H₂O content, this oxygen carrier was used to test the performance of the ethane chemical chaining reaction, using the same test conditions as in Example 1. The C₂H₆ conversion was 92%, and the C₂H₄ selectivity was 71%.

[0019] Example 3

[0020] Following the preparation steps of Example 1, except for a 20% Fe(NO₃)₃·9H₂O content, this oxygen carrier was used to test the performance of the ethane chemical chaining reaction, using the same test conditions as in Example 1. The C₂H₆ conversion was 94%, and the C₂H₄ selectivity was 74%.

[0021] Example 4

[0022] Following the preparation steps in Example 1, the pH value was changed to approximately 9. The oxygen carrier was used to test the performance of the ethane chemical chaining reaction to ethylene under the same test conditions as in Example 1. The C2H6 conversion was 84% ​​and the C2H4 selectivity was 69%.

[0023] Example 5

[0024] Following the preparation steps in Example 1, the pH value was changed to approximately 11. The oxygen carrier was used to test the performance of the ethane chemical chaining reaction to ethylene under the same test conditions as in Example 1. The C2H6 conversion was 82%, and the C2H4 selectivity was 68%.

[0025] Example 6

[0026] Following the preparation steps in Example 1, except that the precipitant was aqueous ammonia, the oxygen carrier was used to test the ethane chemical chaining reaction performance, using the same test conditions as in Example 1. The C2H6 conversion was 92%, and the C2H4 selectivity was 73%.

[0027] Example 7

[0028] Following the preparation steps in Example 1, except that the precipitant was sodium carbonate, the oxygen carrier was used to test the ethane chemical chaining reaction performance, using the same test conditions as in Example 1. The C2H6 conversion was 89%, and the C2H4 selectivity was 71%.

[0029] Example 8

[0030] The preparation steps in Example 1 were followed, and the aging temperature was 60° C. The oxygen carrier was used to test the performance of the ethane chemical chaining reaction to ethylene, using the same test conditions as in Example 1. The C2H6 conversion was 97%, and the C2H4 selectivity was 78%.

[0031] Comparative Example

[0032] NiO / MgO was prepared by precipitation, with a NiO content of 10% by mass, and the calcination temperature was the same as in Example 1. The oxygen carrier was used to test the ethane chemical chaining reaction performance under the same test conditions as in Example 1. The C2H6 conversion was 77%, and the C2H4 selectivity was 52%.

Claims

1. Application of oxygen carrier NiO-Fe2O3 / MgO in ethane chemical chain production of ethylene, characterized by: The active component of the oxygen carrier is NiO, and the C2H6 conversion rate and C2H4 selectivity in the fuel reactor are improved by adding the auxiliary agent Fe2O3. The oxygen carrier uses nickel nitrate, iron nitrate, and magnesium nitrate as precursors, and an alkaline solution as a precipitant. After precipitation, the sample NiO-Fe2O3 / MgO is obtained after aging, filtering, washing, drying and roasting. The reaction temperature in the fuel reactor is 600-1000°C, the reaction temperature in the air reactor is 600-1000°C, and the reaction pressure is 0.1-1MPa.

2. The use according to claim 1, characterized in that: The oxygen carrier is in micro-spherical shape, and the particle size is 10 μm-1000 μm.

3. The use according to claim 1, characterized in that: The mass content of NiO in the oxygen carrier is 0-30% and not zero, the mass content of Fe2O3 is 0-20% and not zero, the mass content of MgO is 50-100%, the alkaline solution is selected from sodium hydroxide, ammonia water, and sodium carbonate, the pH value during precipitation is 9-11, the aging temperature is room temperature to 8°C, the aging time is 2-72 hours, the number of distilled water washings is 2-6 times, the drying time is 1-36 hours, and the calcination is performed at 400-1000°C for 2-15 hours.

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