Yüksek kükürt içeren linyitlerin kimyasal çember gazlaştirma süreçleri için siniflandirma ve tepkime testleri.

The objective of this study was to characterize and to determine the gasification reactivity of Tuncbilek lignites. The ultimate analysis of Tuncbilek lignite revealed that the elemental composition is 37.7% C, 3.6% H, 1.6% N, and 5.4% S, while the proximate analysis indicated 4.7 ± 0.9% moisture 27.9 ± 0.1% volatiles and 37.9 ± 0.2% ash. In this context, four different reactions during gasification namely, pyrolysis, oxidation, hydrogenation, and wet air oxidation were investigated separately. Carbon residues of all these processes were analyzed by XRD, DRIFTS, and 1H and 13C (CP) NMR spectroscopy in order to associate between chemical structure and reactivity. A semi-batch reactor system was used for pyrolysis, oxidation, and hydrogenation experiments, while a high-pressure batch reactor was used for wet air oxidation experiments. Pyrolysis and oxidation experiments revealed that carbon conversion of Tuncbilek lignite is quite high in the presence of oxygen. In addition, hydrogenation experiments displayed that the sulfur removal is the most efficient in the presence of gas phase hydrogen. On the other hand, desulfurization yield of wet air oxidation reaction at 5 bar and 150ºC, was lower than hydrodesulfurization yields. The results of the experiments indicated that high pressure and temperature are necessary to enhance the yield. Co and Pb based pure and mixed metal oxides were investigated as oxygen source and sulfur trapping agents for chemical looping systems. The oxygen transfer potential of Co-Pb metal oxides was monitored by TGA and the maximum weight loss was recorded when coal to metal oxide ratio is higher than 1. Additionally, XRD revealed sulfur capturing ability of these oxides during both pyrolysis and oxidation processes. A process flow diagram is proposed to utilize the mixed metal oxides as chemical looping agents for oxygen and sulfur transferPh.D. - Doctoral Progra

In situ and downstream sulfidation reactivity of PbO and ZnO during pyrolysis and hydrogenation of a high-sulfur lignite

Economical valorization of low quality, high sulfur feedstocks is an important challenge. Most of the valorization processes start from pyrolysis, with a significant amount of evolution of sulfur containing compounds. This study addresses in situ and downstream sulfur capture ability of lead oxide (PbO) in comparison to zinc oxide (ZnO) during the pyrolysis of high-sulfur Tuncbilek lignite. In order to assess the role of hydrogen in sulfur capture, hydrogenation experiments were also performed. Sulfidation reaction thermodynamics of PbO and ZnO was compared to most commonly used metal oxides for sulfur capture i.e., FeO, MnO, and CaO. The equilibrium conversions indicated superior performance of PbO and ZnO towards sulfidation reactions at high temperatures. Thermodynamic superiority of PbO sulfidation encouraged us to investigate the PbO as a new sulfur sorbent for hot gas desulfurization. The experimental verification of the high temperature sulfidation ability of PbO and ZnO was performed using high-sulfur Tuncbilek lignite under semibatch conditions. The final compounds formed after each process were observed by X-ray diffractometer (XRD) and Diffuse Reflectance Infrared Fourier Transformation Spectroscopy (DRIFTS). Experiments revealed that PbO can be promising candidate as hot gas sulfur trap during pyrolysis and hydrogenation processes, while ZnO can hold up sulfur only in the presence of hydrogen. Furthermore, both PbO and ZnO show the superior sulfur capture performance in the presence of hydrogen when they were used as adsorbents located after the reactor (downstream) at ambient conditions. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved

Catalytic Role of Pyrite on Hydrodesulfurization of Lignite and Asphaltite

Pyrite, FeS2 , naturally present in solid fuels can act as catalysts during hydrogenation processes. In general, metal sulfide catalysts are used as hydrogenation and hydrodesulfurization processes of petroleum fractions. The defects in crystal lattice were considered as the responsible parts of catalytic activity. Therefore, the presence of metal sulfide active sites in the structure increases the process efficiency. Since pyrite is a metal sulfide present in the coal structure, Guin et al. reported a higher reaction rate in the presence of pyrite during hydrogenation process [1]. In this study, catalytic effect of pyrite has been investigated by hydrogenation of a high sulfur Turkish lignite and asphaltite at atmospheric pressure. The first results of hydrogenation experiments for Tuncbilek lignite with high pyrite content (2.6% in weight) revealed that H2 reduction decreases the sulfur contents considerably. Additionally, the amount of residual carbon decreased as observed from the decrease in CO2 formation rate of hydrogenation residue during TPO. These effects are interpreted for the catalytic effect of pyrite [2]. Hydrodesulfurization of Şırnak asphaltite with 1.59% pyrite, is carried out under 100 sccm flow of 10% H2 and balance N2 . Gas and liquid product analysis indicated that hydrogenation of asphaltite results in a significant decrease in total sulfur while producing nearly 20% liquid fuel, which contains organics from C6 to C26