تولید گاز سنتز به‌وسیله اکسیداسیون جزئی متان و تبدیل CO2 به‌روش چرخه شیمیایی

نوع مقاله : مقاله پژوهشی

نویسندگان

گروه تبدیلات گازی، پژوهشکده گاز، پژوهشگاه صنعت نفت، تهران، ایران

چکیده

گاز سنتز را می‌توان از گاز طبیعی (یا متان) به کمک بخار یا اکسیژن تولید کرد. فرآیندهای موجود از جمله ریفرمینگ کاتالیستی و خودگرمایی با مصرف انرژی و هزینه بسیار بالایی روبرو هستند. به‌عنوان یک فرآیند جایگزین، چرخه شیمیایی ریفورمینگ دارای ویژگی‌هایی از قبیل عدم نیاز به اکسیژن خالص، انتشار کم CO2 و یکپارچگی بهتر فرآیند است. در کار حاضر به منظور تولید گاز سنتز برای احیای حامل‌های اکسیژن پروسکایتی از متان در یک فرآیند چرخه شیمیایی دینامیکی استفاده شده است و پس از آن، اکسیداسیون مجدد توسط CO2 و هوا انجام می‌شود. حامل اکسیژن پروسکایتی به‌روش احتراقی ساخته شده و در سامانه رآکتوری بستر ثابت به‌صورت دینامیک آزموده شد. در رآکتور احیاء در مدت زمان محدود، گاز سنتز تولید گردید. میزان CO2 تولیدی در این روش کمتر از 5% است که در مقایسه با روش‌های معمول کمتر است. با ادامه واکنش احیاء، هیدروژن خالص تولید شده اما کک نیز تولید می‌گردد. بنابراین، احیای حامل اکسیژن به‌صورت ناقص انجام گردید. برای جبران اکسیژن‌های مصرف شده، در بخش اکسیداسیون، ابتدا گاز گلخانه‌ای CO2 و پس از آن هوا به رآکتور تزریق گردید. علاوه‌بر این، سوزاندن کک‌های تشکیل شده نیز همزمان انجام می‌گردد. نتایج نشان می‌دهند که تبدیل متان به حدود 90% در مدت min 30 می‌رسد. در min 17 ابتدای واکنش اکسیداسیون توسط CO2، بخش قابل توجه CO2 به CO تبدیل می‌گردد. در سیکل اکسیداسیون توسط هوا، برای بازیابی اکسیژن شبکه و سوختن کک حدود min 20 زمان نیاز است. نتایج نشان می‌دهد که هم CO2 و هم هوا نه تنها قابلیت سوزاندن و حذف کک را دارند بلکه تأمین‌کننده اکسیژن‌های از دست رفته شبکه هستند.
 

کلیدواژه‌ها


عنوان مقاله [English]

Syngas Production by Partial Oxidation of Methane and CO2 Conversion Using Chemical Looping Method

نویسندگان [English]

  • seyed shabbir mousavi
  • Hadi ebrahimi
  • Yahya Zamani
Gas Conversion Group, Gas Research Division, Research Institute of Petroleum Industry (RIPI), Tehran, Iran
چکیده [English]

Syngas (a mixture of hydrogen and carbon monoxide) could be produced by natural gas (methane) with steam or oxygen. The current methods such as catalytic reforming and autothermal deal with high energy consumption and cost demands. As an alternative, chemical looping reforming could be used with versatile features such as no need of pure oxygen, low CO2 reduction and better process integration. In the current article, a dynamic chemical looping process is employed to produce syngas resulted in the reduction of a perovskite oxygen carrier from methane. After that, the re-oxidation is performed in two steps with both CO2 and Air. The perovskite catalyst, synthesized by combustion method, was tested in a fixed-bed reactor in a dynamic manner. In the reduction reactor, however, the syngas was produced in a limited time. The CO2 produced during the reduction was below 5%, which is lower than that of the common methods. By continuing the reduction reactions, a high amount of hydrogen is produced, but solid coke is formed too. Hence, the reduction is partially performed. To compensate the consumed oxygen of the perovskite lattice, at first, the greenhouse gas of CO2 is injected into the reactor, followed by oxidation by Air. Moreover, the coke removal (combustion) is performed during these two oxidation steps. The results show that, the methane conversion is reached to 90% during the first 30 min of the reduction. A vast majority of CO2 is converted to CO in only 17 min of the first oxidation step. In addition, the time that is required for air-re-oxidation to remove the cokes is equal to 20 minutes. Finally, according to the obtained results, both CO2 and Air could not only remove the formed solid carbon, but it also compensated the oxygen vacancies inside the lattice.
 

کلیدواژه‌ها [English]

  • Syngas
  • Methane Partial Oxidation
  • Chemical Looping Reforming
  • CO2 Conversion
  • Perovskite oxygen carrier
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