Synthesis, Characterization and Evaluation of Some Polymeric Nano-Composites and Their Applications in Petroleum Industry

Abstract

Hydrogen sulfide gas is considered the most harmful gas associated with the production of natural gas and crude oil. This gas leads to many problems, including health, occupational safety and corrosion in the pipes during their transportation and distribution. Accordingly, it is necessary to remove it and reduce its concentration in natural gas to the environmentally permitted limit. The removal of hydrogen sulfide gas from the natural gas was performed by several ways including; physical and chemical methods, adsorption on the particles surfaces and the absorption by liquid solvents. To achieve this goal, three copolymers based on acrylamide and vinyl acetate in three different molar ratios, CdO nanoparticles and four nanocomposites were synthesized. This thesis comprises three main chapters as follows:  Chapter 1 (Introduction) • In this chapter, hydrogen sulfide gas background, emission sources and its problems on human health, equipments attack, environment and economy impacts and the available methods to treat H2S gas in different production fields are presented.  Chapter 2 (Experimental) A. Synthesis of polymers, CdO and their composites • This chapter discusses the synthesis of three copolymers based on acrylamide (AM) and vinyl acetate (VA) with three different molar ratios (3:1, 1:1 and 1:3 named AMVA1, AMVA2, and AMVA3, respectively). Also, the preparation (chemical method) of CdO nanoparticles of 8.8 nm was achieved. Also, the preparation of CdS using H2S gas as a natural source of sulfur is described. Moreover, four types of CdO /copolymer were prepared. B. Characterization The composition of the prepared samples was elucidated using different techniques: - 1. Furrier Transmittance Infra-Red (FT-IR): The chemical structures of the prepared polymers were characterized using a Nicolet FT-IR, spectrometer [Thermo Fisher Scientific (USA)]. 2. Molecular weight determination: The molecular weights of the prepared polymers were determined by Gel permeation chromatography (GPC). Also, the number of acrylamide units in the synthesized copolymer was emphasized by nitrogen content determination using Kjeldahl method. 3. X-ray diffraction (XRD): XRD of CdO, CdS and CdO/copolymer and CdS/copolymer was measured using Shimazdu 6000 Series, Cu-Kα radiation λ = 1.5418 Å. 4. Scan Electron microscopy (SEM): The surface images of the polymers, CdO, CdS and their composites were performed using Environmental Scanning Electron Microscopy (XL30 ESEM-FEG). C. Evaluation A new method was designed to evaluate the prepared samples as H2S scavenger and determine sulfur loading using a field simulation designed in natural gas applications.  Chapter 3 (Results and Discussion) In this chapter, the focus is on discussing the effects of different parameters such as; 1) Type of the applied polymer adsorbents, 2) Inlet H2S concentration in gas streams, 3) Gas flow rate, 4) Operating temperature, 5) CO2 concentration and 6) CdO/AMVA2 nanocomposite on the breakthrough curves. The results obtained revealed the following: - 1) Effect of polymer adsorbents The breakthrough curves of the prepared polymer adsorbents at volumetric flow rate 1 L/h, an inlet H2S concentration 10 ppm, constant pressure 1 atm. and operating temperature 45oC in the first cycle showed that the sulfur loading for AMVA1, AMVA2 and AMVA3 are 0.3, 0.6 and 1%, respectively. This may be attributed to the chemical structure of polymer adsorbents, whereas, the sulfur loading of the polymer sample is directly proportional to the acrylamide content of the polymer. The increases of acrylamide units mean increase the active nitrogen atoms which are responsible for H2S scavenging, by their lone pairs of electrons. 2) Effect of changing inlet H2S concentration The results revealed that the slope of the breakthrough curve increases with increasing initial H2S concentration and the period of time between breakthrough time (tb) and complete saturation time (tc) decreases. A longer bed, or more active sites, are needed to consume a given amount of H2S within the same time period. 3) Effect of inlet gas flow rate change From the results obtained, it was found that H2S outlet concentration was affected by the H2S feed flow rate, whereas, a high retention time resulting from a low gas flow rate caused an increase in the H2S removal percentage.