Catalytic Activities and Properties for the Desulfurization and Hydrocracking of Light Cycle Oil : 접촉분해경유의 탈황과 수소화분해에 관한 촉매의 활성 및 특성 연구

다국어 초록 (Multilingual Abstract)

This study includes various catalytic processes applied for upgrading light cycle oil (LCO). In order to increase the sulfur removal capability, three approaches have been employed by hydrodesulfurization (HDS), oxidative desulfurization (ODS) and combined ODS and HDS. Also we have applied Ni2P catalysts for the light cycle oil hydrotreating and hydrocracking into BTX. Characterizations of the fresh and spent catalysts were made by BET, CO-uptake, NH3-TPD, XRD, TEM, TGA, ICP-AES and EXAFS spectroscopy.
Firstly, the Ti catalysts were prepared by grafting method to apply for the ODS of LCO, resulting in high ODS activity for LCO feed with the conversion of 95 %, at TBHP/S molar ratio 2.5 and 353 K. The mesoporous Ti-SBA-15 exhibited better performance in the ODS of model refractory sulfur compounds than microporous Ti-Beta due to its easy access for the bulky molecules. The removal of oxidized species in the LCO ODS products was carried out by a solvent extraction method using different aprotic solvents. The increase in the solvent/LCO ratio and number of extraction stages, the desulfurization of LCO increases, but the recovery of LCO from the extractions of oxidized products was decreased due to the polyaromatic hydrocarbons in LCO partially extracted along with oxidized sulfur compounds in the solvent extraction step.
Secondly, the nitrogen compounds strongly inhibit the ODS of refractory sulfur compounds while addition of aromatic and aprotic solvent enhance the ODS activity and stability, which were attributed to the high solubility of the oxidized S or N compounds. Overall, the ODS of refractory sulfur compounds over the Ti-SBA-15 catalyst was highly dependent upon the solubility of the oxidized products in the solvent, and the presence of polycyclic aromatics compounds in LCO feed plays a beneficial role in restricting the product deposition on the catalyst surface.
Thirdly, the Ni2P/SBA-15 and NiMoS/Al2O3 catalysts were prepared and applied for the HDS of LCO. The Ni2P/SBA-15 gave an HDS conversion of 99 % and an HDN conversion of 91 %, which were much higher than those of a NiMoS/Al2O3 catalyst which gave an HDS conversion of 96 % and an HDN conversion of 78 % based on the same reaction conditions.
Fourthly, the combined sulfur removal process of ODS and HDS was employed for S removal of LCO, resulting in high HDS activity for LCO feed with the HDS conversion of 99.8 % and an HDN conversion of 98.1% over Ni2P/SBA-15. The model reaction test with DBT, DBTS, indole and oxindole revealed that the oxidized nitrogen compounds are higher HDN reactivity than those of nitrogen, leads to reduced competitive reaction between HDN and HDS.
Fifthly, we have applied Ni2P catalysts for the LCO hydrotreating and hydrocracking into BTX. The LCO has many polyaromatic hydrocarbons and high sulfur, nitrogen contents. The model reaction tests for the HCK of 1-methylnaphthalene demonstrated that the nitrogen compounds in the feed decrease the BTX yield due to the nitrogen compounds adsorbed the acid sites of catalyst leads to reduced exposed acid sites, resulting in decrease in catalyst activity. Therefore, N compounds must be pre-treated to remove the heterocyclic compounds that can act as a catalytic poison. The Ni2P/SBA-15 catalyst applied for hydrotreating of LCO to remove S and N compounds. After the hydrotreating, the Ni2P/Beta catalysts applied for hydrocracking of pre-treated LCO.
Sixthly, the hydrocracking of 1-MN in the presence and absence of polyaromatic hydrocarbon into BTX has been studied over Ni2P/Beta. In presence of 3-Ar the coke deposition was accelerated on the catalyst surface, leading to reduced exposed acid sites, and resulting in the decrease in catalyst activity. The desilication of zeolite Beta led to the increased mesopore volume and the total amount of acid sites. Compared to the Ni2P/Beta zeolite, the Ni2P/DS-Beta showed high activity for hydrocracking of polyaromatic hydrocarbon and PFO.

목차 (Table of Contents)

• Chapter1 Introduction 1
• 1.1. Background 1
• 1.1.1. Growing demands on ultra-low sulfur diesel (ULSD) 1
• 1.1.2. Limitations in conventional hydrodesulfurization (HDS) 4
• 1.1.3. Limitations in HDS of light cycle oil (LCO) 5
• 1.1.4. Oxidative desulfurization (ODS) 6
• 1.1.5. Hydrocracking (HCK) of Polyaromatic hydrocarbon (PAH) into BTX 8
• 1.2. Catalysts 9
• 1.2.1. HDS catalysts 9
• 1.2.2. ODS catalysts 11
• 1.2.3. HCK catalysts 12
• 1.3. Experimental details 12
• 1.3.1. Preparation of the ODS catalyst 12
• 1.3.2. Preparation of the HDS catalyst 13
• 1.3.3. Preparation of the HCK catalyst 14
• 1.3.4. Characterization of catalysts 15
• 1.3.5. Activity test for ODS of LCO 18
• 1.3.6. Activity test for HDS of LCO 21
• 1.3.7. Activity test for HCK of 1-MN 23
• 1.4. Objectives 24
• 1.5. Overview 25
• Chapter2 Factors Influencing Oxidative Desulfurization of Light Cycle Oil over Supported Titanium Catalysts 34
• 2.1 Introduction 34
• 2.2 Experimental 36
• 2.2.1. Materials and catalysts preparation 36
• 2.2.2. Catalyst characterization 39
• 2.2.3. Activity test for ODS of model feed oils and LCO 39
• 2.2.4. Solvent extraction measurements 40
• 2.3 Results and Discussion 41
• 2.3.1. Effect of support type on the ODS activity 41
• 2.3.2. Effect of oxidant type on the ODS activity 44
• 2.3.3. Effect of TBHP/S ratio on the ODS activity 44
• 2.3.4. Effect of Ti content on the ODS activity 47
• 2.3.5. The ODS of LCO 49
• 2.3.6. Solvent extraction 52
• 2.4 Conclusions 60
• Chapter3 Effects of Nitrogen Compounds, Aromatics, and Aprotic Solvents on the ODS of Light Cycle Oil over Ti-SBA-15 Catalyst 64
• 3.1 Introduction 64
• 3.2 Experimental 66
• 3.2.1. Materials and catalysts preparation 66
• 3.2.2. Catalyst characterization 68
• 3.2.3. Solubility measurements 68
• 3.2.4. Activity test 69
• 3.3 Results and Discussion 71
• 3.3.1. Effect of nitrogen compounds on the ODS 71
• 3.3.2. Effect of aromatic solvents on the ODS 75
• 3.3.3. Effect of aprotic solvent on the ODS 76
• 3.3.4. Solubility of oxidized S and N products in aromatics or aprotic solvents 79
• 3.3.5. Oxidative desulfurization of LCO 82
• 3.4 Conclusions 88
• Chapter4 Combination of ODS and HDS for Deep Desulfurization of Light Cycle Oil 92
• 4.1 Introduction 92
• 4.2 Experimental 94
• 4.2.1. Materials 94
• 4.2.2. Preparation of the ODS catalyst 95
• 4.2.3. Preparation of the HDS catalyst 96
• 4.2.4. Catalyst characterization 97
• 4.2.5. Activity test of ODS for LCO 97
• 4.2.6. Activity test of HDS for LCO and oxidized LCO 98
• 4.3 Results and Discussion 99
• 4.3.1. HDS and HDN activity test of catalysts for LCO 99
• 4.3.2. HDS and HDN activity test of catalysts for oxidized LCO 102
• 4.4 Conclusions 108
• Chapter5 Activity of Ni2P/Beta for Hydrocracking of 1-methylnaphthalene into BTX 112
• 5.1 Introduction 112
• 5.2 Experimental 113
• 5.2.1. Materials and catalysts preparation 114
• 5.2.2. Catalyst characterization 115
• 5.2.3. Activity test for hydrocracking of 1-methylnaphthalene 116
• 5.3 Results and Discussion 116
• 5.3.1. Effect of temperature and pressure on the 1-MN hydrocracking reaction 121
• 5.3.2. Effect of S and N compounds on the 1-MN hydrocracking reaction 121
• 5.4 Conclusions 132
• Chapter6 Effect of Desilication of Beta Zeolite for Hydrocracking of Pyrolysis fuel oil into BTX 136
• 6.1 Introduction 136
• 6.2 Experimental 137
• 6.2.1. Materials and catalysts preparation 137
• 6.2.2. Catalyst characterization 139
• 6.2.3. Activity test for hydrocracking of 1-MN and PFO 140
• 6.3 Results and Discussion 141
• 6.3.1. Physical property of desilicated Ni2P/Beta. 141
• 6.3.2. Hydrocraking activity of 1-MN 147
• 6.3.3. Hydrocraking activity of PFO 149
• 6.4 Conclusions 150
• Chapter7 Conclusion 158
• Abstract (in Korean) 158