Synthesis of Hierarchical ZSM-5 Zeolites with Unique Morphologies and Tunable SiO2/Al2O3 Ratios for Dry Reforming of Methane. Masters thesis, King Fahd University of Petroleum and Minerals.

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Arabic Abstract

يُعَدُّ إِصْلَاحُ الْمِيثَانِ بِثُنَائِيِّ أُكْسِيدِ الْكَرْبُونِ (DRM) وَاحِدًا مِنَ الْأُسْلُوبِ المُسْتَدَامِ لِاسْتِغْلَالِ غَازَاتِ الدَّفِيبِ وَإِنْتَاجِ غَازِ التَّرْكِيبِ، وَهُوَ غَازٌ ذُو أَهَمِّيَّةٍ صِنَاعِيَّةٍ فِي صِنَاعَاتِ الْمِيثَانُولِ وَالْوَقُودِ التَّرْكِيبِيِّ. وَيُعْتَبَرُ هَذَا النَّهْجُ وَسِيلَةً فَعَّالَةً لِلتَّقْلِيلِ مِنْ انْبِعَاثِ غَازَاتِ الدَّفِيبِ الضَّارَّةِ بِالْغِلَافِ الْجَوِّيِّ، مَعَ إِضْفَاءِ قِيمَةٍ كِيمْيَائِيَّةٍ. وَمَعَ ذَلِكَ، فَإِنَّ مُوَصِّلَاتِ النِّيكِلِ تَتَعَرَّضُ لِلتَّثْبِيطِ السَّرِيعِ عِنْدَ دَرَجَاتِ الْحَرَارَةِ الْعَالِيَةِ لِـ DRM (٧٠٠–١٠٠٠°م) بِسَبَبِ تَكَوُّنِ السُّخَامِ وَتَكَبُّدِ جُزَيئَاتِ النِّيكِلِ، مِمَّا يُعِيقُ تَجَارَةَ هَذِهِ التِّقْنِيَةِ وَيُقَلِّلُ مِنْ فَاعِلِيَّتِهَا الصِّنَاعِيَّةِ. تَسْعَى هَذِهِ الدِّرَاسَةُ إِلَى تَطْوِيرِ مُوَصِّلٍ مَتِينٍ وَمُسْتَقِرٍّ لِإِصْلَاحِ الْمِيثَانِ بِالْجَفَافِ بِصُورَةٍ أَكْثَرَ فَاعِلِيَّةً لِلتَّطْبِيقَاتِ الصِّنَاعِيَّةِ. يُقَدِّمُ هَذَا الْبَحْثُ دِرَاسَتَيْنِ فِي تَطْوِيرِ دَعَائِمِ زِيُولَايْتِ ZSM-5 الْهَرَمِيَّةِ بِهَنْدَسَاتٍ فَرِيدَةٍ، وَهِيَ: الشَّكْلُ الْكُرَوِيُّ (ZSM-5-S) وَالشَّكْلُ حَادُّ الْحَافَةِ (ZSM-5-K)، لِاسْتِخْدَامِهَا فِي مُوَصِّلَاتِ النِّيكِلِ لِإِصْلَاحِ الْمِيثَانِ إِلَى غَازِ التَّرْكِيبِ. فِي الدِّرَاسَةِ الْأُولَى، تَمَّ تَخْلِيقُ دَعَامَةٍ هَرَمِيَّةٍ كُرَوِيَّةٍ لِـ ZSM-5 بِاسْتِخْدَامِ طَرِيقَةٍ مَائِيَّةٍ حَرَارِيَّةٍ تَصَاعُدِيَّةٍ مَعَ تَوْجِيهٍ ثُنَائِيٍّ. أَظْهَرَتِ الْمُوَصِّلَةُ Ni/ZSM-5-S مِسَاحَةً سَطْحِيَّةً عَالِيَةً، وَمَسَامِيَّةً وَاسِعَةً، وَتَوَزُّعًا مُمْتَازًا لِلنِّيكِلِ، مِمَّا أَدَّى إِلَى نِسَبِ تَحَوُّلٍ بَلَغَتْ ٧٨.٠٪ لِلْمِيثَانِ وَ٨٢.٥٪ لِثُنَائِيِّ أُكْسِيدِ الْكَرْبُونِ عِنْدَ دَرَجَةِ حَرَارَةٍ تُقَدَّرُ بِـ ٧٠٠°م، مَعَ أَدَاءٍ مُسْتَقِرٍّ لِمُدَّةِ ٢٢ سَاعَةً. وَقَدْ أَكَّدَتِ التَّحْلِيلَاتُ الطَّيْفِيَّةُ وَالْمَجْهَرِيَّةُ تَفَاعُلًا قَوِيًّا بَيْنَ الْمَعْدِنِ وَالدَّعَامَةِ، وَتَقْلِيلًا فِي تَكَوُّنِ السُّخَامِ، فِيمَا دَلَّتْ تَحْلِيلَاتُ DRIFTS عَلَى أَنَّ آلِيَّةَ التَّفَاعُلِ تَتَّبِعُ نَمُوذَجَ لَانْجْمِير–هِنْشِلْوُودْ. أَمَّا الدِّرَاسَةُ الثَّانِيَةُ، فَقَدْ تَرَكَّزَتْ عَلَى تَخْلِيقِ دَعَائِمَ ZSM-5 حَادَّةِ الْحَافَةِ وَتَعْدِيلِهَا عَنْ طَرِيقِ اسْتِبْدَالِ الْبُوتَاسْيُومِ وَمُعَالَجَةِ هِيدْرُوكْسِيدِ الأَمُونِيُومِ. وَقَدْ أَظْهَرَتِ الْمُتَغَيِّرَاتُ (5NR-K، 5NNR-K، 5NNR-H) نِسَبَ تَحَوُّلٍ أَوَّلِيَّةٍ تَفُوقُ ٨٥٪، وَانْتِقَائِيَّةً عَالِيَةً لِغَازِ التَّرْكِيبِ، وَقَاوَمَتِ التَّكَوُّنَ الْكَرْبُونِيَّ خِلَالَ اخْتِبَارِ الاسْتِقْرَارِ لِمُدَّةِ ٢٤ سَاعَةً. وَقَدْ بَيَّنَتِ التَّحْلِيلَاتُ أَنَّ تَعْدِيلَ الْهَنْدَسَةِ الشَّكْلِيَّةِ وَكِيمْيَاءِ السَّطْحِ لَهُ أَثَرٌ حَرِجٌ فِي قَابِلِيَّةِ اخْتِزَالِ الْمُوَصِّلِ، وَقَاعِدِيَّتِهِ، وَأَدَائِهِ الْعَامِّ. وَبِشَكْلٍ عَامٍّ، تُؤَكِّدُ كِلْتَا الدِّرَاسَتَيْنِ فَاعِلِيَّةَ التَّصْمِيمِ الْمَنْطِقِيِّ لِلْهَنْدَسَةِ الشَّكْلِيَّةِ وَالْكِيمْيَائِيَّةِ فِي تَحْسِينِ مُوَصِّلَاتِ النِّيكِلِ لِإِصْلَاحِ الْمِيثَانِ. وَقَدْ أَظْهَرَتِ الْأَنْظِمَةُ الْمُطَوَّرَةُ عَلَى أَسَاسِ ZSM-5 الْهَرَمِيَّةِ نَشَاطًا عَالِيًا، وَثَبَاتًا حَرَارِيًّا قَوِيًّا، وَتَقْلِيلًا لِتَرَسُّبِ الْكَرْبُونِ، مِمَّا يُسَاهِمُ فِي تَقَدُّمِ التِّقْنِيَاتِ التَّحْفِيزِيَّةِ الْمُسْتَدَامَةِ لِاسْتِغْلَالِ غَازَاتِ الدَّفِيبِ وَإِنْتَاجِ غَازِ التَّرْكِيبِ، مَعَ إِمْكَانِيَّةٍ كَبِيرَةٍ لِلتَّطْبِيقِ الصِّنَاعِيِّ.

English Abstract

Syngas is produced by carbon dioxide reformation of methane (DRM), which is a sustainable method of using greenhouse gases and generating useful chemical feedstocks, an efficient approach to reducing the emissions of gases harmful to the atmosphere (greenhouse gases) whilst generating an important industrial feedstock. Due to coke formation and sintering of nickel-based catalysts, there is often a rapid deactivation of catalysts at DRM temperatures (700-1000 °C), making the commercialization of DRM technology very difficult. This research seeks to develop a robust catalyst for efficient dry reforming of methane to syngas for industrial applications. This thesis presents a two-part study on the development of hierarchical ZSM-5 zeolite supports with distinct morphologies as spherical (ZSM-5-S) and knife-edged (ZSM-5-K), for use in nickel-based catalysts for the dry reforming of methane (DRM) to syngas. In the first study, a spherical hierarchical ZSM-5 support was synthesized via a bottom-up hydrothermal method incorporating a dual-templating strategy. The resulting Ni/ZSM-5-S catalyst exhibited a high surface area, enhanced mesoporosity, and excellent Ni dispersion, achieving CH₄ and CO₂ conversions of 78.0% and 82.5% respectively at 700 °C, with stable performance over 22 hours. Characterization confirmed strong metal-support interaction and reduced coke formation, while DRIFTS analysis suggested a Langmuir–Hinshelwood reaction mechanism. The second study focused on the synthesis of knife-edged ZSM-5 supports and their modification using potassium exchange and ammonium hydroxide treatment. These variants (5NR-K, 5NNR-K, 5NNR-H) demonstrated high initial conversions (>85%), enhanced syngas selectivity, and improved resistance to coking during 24-hour stability tests. Morphological tuning and surface chemistry modification were shown to critically influence catalyst reducibility, basicity, and overall DRM performance. Collectively, both studies highlight the effectiveness of rational morphological and chemical design in enhancing Ni-based DRM catalysts. The hierarchical ZSM-5-based systems developed here exhibited high activity, strong thermal stability, and reduced carbon deposition. These findings contribute to advancing sustainable catalytic technologies for greenhouse gas utilization and syngas production, with strong potential for industrial application.

Item Type:	Thesis (Masters)
Subjects:	Chemistry Chemical Engineering Research > Petrochemicals
Department:	College of Chemicals and Materials > Chemistry
Committee Advisor:	GANIYU, SAHEED ADEWALE
Committee Members:	Alhooshani, Khalid Rashed and Tanimu, Abdulkadir
Depositing User:	YAHUZA ABDULAI (g202214280)
Date Deposited:	22 Jun 2025 08:13
Last Modified:	22 Jun 2025 08:13
URI:	http://eprints.kfupm.edu.sa/id/eprint/143556