Catalytic destruction of nitrogen containing pollutants
Supervisor: prof. Ing. Lucie Obalová, Ph.D.
Nitrogen oxides (N2O, NO, NO2) and NH3 are significant pollutants. Many current technologies for reducing these substances in waste gases are economically demanding or require the presence of a reducing agent (ammonia, urea, hydrocarbons) that can lead to emissions of other pollutants (ammonia slip). It is therefore desirable to develop and test new methods for reducing emissions of these components.
The main task will be an experimental study of catalytic degradation of nitrogen oxides without the use of a reducing agent and/or oxidation of NH3 on catalysts containing selected transition metals and a description of the physical-chemical properties of catalysts by available analytical techniques (chemical analysis, X-ray diffraction, physical nitrogen sorption, temperature-programmed desorption and reduction, etc.). The aim of the thesis will be to assess the effectiveness and stability of the materials studied, to clarify the mechanism of ongoing reactions and the relationships between the properties of catalysts and their activity and selectivity, and to optimize the method of catalyst preparation.
Removal of persistent pollutants from sewage sludge during their various technological processing with the aim of further utilization of sludge in agriculture
Supervisor: prof. Ing. Lucie Obalova, Ph.D.
Specialist supervisor: Mgr. Martina Vráblová, Ph.D.
The doctoral thesis will be focused on the degradation efficiency of persistent pollutants present in sewage sludge during various further processing of the sludge. It includes technologies used or potentially usable in wastewater treatment plants (sanitization, drying, heat treatment, etc.). The work will be focused on monitoring the persistent pollutants in the sewage sludge followed by the verification of the effect of individual technologies on the decrease in concentration or transformation of the persistent pollutants (especially drugs and other organic compounds).
Chemical Recycling of Waste Plastics by Catalytic Pyrolysis over Structured Catalysts
Supervisor: prof. Ing. Lucie Obalova, Ph.D.
Specialist supervisor: Dr.-Ing. Amer Inayat
Chemical recycling is an important alternative to mechanical processes for the recycling of plastic wastes. It offers the possibility of transforming waste plastics into important chemicals which can be used as feedstocks in chemical and petrochemical industries. Thus, chemical recycling of waste plastics has the potential of contributing to resource conservation as well as to waste minimization. Catalytic pyrolysis is an attractive process for the chemical transformation of waste plastic into useful chemicals. The product selectivity during pyrolysis process can be tuned by choosing the appropriate process parameters, catalytic materials as well as reactor configuration.
Structured zeolite composites are interesting catalytic materials for the catalytic pyrolysis of waste plastics. They can combine the textural and catalytic properties of zeolites with the geometry (e.g. geometric specific surface) and material related properties (e.g. thermal conductivity) of structured supports. In this regard, a thin layer of zeolite catalyst on a thermally conductive support (e.g. SiC foam) can not only reduce the diffusion path length and maximize the catalyst utilization but also improve the heat transfer inside the reactor. The enhanced mass and heat transfer achieved can further improve the activity and stability of the catalyst.
The goal of this thesis includes preparation/characterization of zeolite-foam catalyst, testing/determining the optimal conditions of catalytic pyrolysis for selected waste plastics and finding the correlations between physico-chemical and catalytic properties.
Requirements:
- Completed master degree in chemical/process engineering, material science, chemistry.
- Knowledge of analytical methods such as, TGA, XRD, BET, TPD and GC/GC-MS and previous experience with zeolite synthesis/coating would be advantageous but not required.
Possibilities of anaerobic co-fermentation of biowaste or energy biomass with waste or purposefully grown algae biomass
Supervisor: prof. Ing. Lucie Obalova, Ph.D.
Specialist supervisor: Ing. Jiří Rusín, Ph.D.
Algae appear to be a promising source of biomass for the production of biofuels. Algae can be anaerobically decomposed relatively easily to produce biogas and fertilizer, but the high-water content reduces the overall efficiency of the process. The possibilities and processes of obtaining algae biomass will be studied, for example with the use of waste gases from industrial processes. The processes of pretreatment of the green mass of algae with the aim of increased degradability in the process of anaerobic digestion will be described. The theoretical advantages and disadvantages of co-fermentation of algae with biowaste or conventional energy biomass will be evaluated. At least one experiment of continuous algae biomass production with subsequent processing by anaerobic digestion will be carried out. Batch digestion tests will verify the kinetics of biogas production from algae. (Semi)continuous processes will verify the co-fermentation of algae with selected types of biowaste or energy biomass. If possible, the (semi)continuous mono-fermentation of algae will also be verified. The practical applicability and benefits of algae co-processing in biogas stations will be evaluated.
Application in anaerobic digestion of chemically modified biochar and pyro-oil generated from digestate
Supervisor: prof. Ing. Lucie Obalova, Ph.D.
Specialist supervisor: Ing. Jiří Rusín, Ph.D.
Zero-waste approach coupling anaerobic digestion and pyrolysis requires the transformation of the organic matter contained in the digestion solid effluent via pyrolysis to valuable products. The products consist of a pyro-oil including an enriched-in-organics water phase that can be valorized for biogas generation and a solid material (“biochar”) which can be potentially used in several applications e.g. bioremediation, gas cleaning, soil amelioration or as additive in anaerobic digestion. Biochar deriving from biomass pyrolysis has been reported to have a positive effect on anaerobic methane generation. Biochar produced from the solids of the effluent of anaerobic digestion appeared to have lower efficiency.
The research during PhD study aims to close the cycle between the two processes by initially valorizing the water-phase of pyrolysis oil in biogas production and secondly find appropriate pathways of pretreatment, mainly chemical, for the digestate-derived char to optimize the catalytic activity in an anaerobic digestion system. Laboratory experiments of pyrolysis of separated digestate solids and experiments of its application to laboratory fermenters will be carried out.