One highlight of the Spring 2016 Biannual Meeting was the Call 2 Project updates session. The session took place in the Pioneer Theatre, Manchester Conference Centre, on Wednesday, 13 April 2016. The Call 2 Projects are fundamental and multidisciplinary CCS research projects that address research needs identified by the Advanced Power Generation Technology Forum (APGTF) and the DECC CCS Roadmap for Innovation and R&D. The session was dedicated to sharing key project outcomes and progress made on two Call 2 Projects. This provided an opportunity for other CCS researchers and stakeholders to learn more about the projects as well as allowing them to engage with the Call 2 projects investigators.
The project investigators gave their presentations in the following order:
Advanced Sorbents for CCS via Controlled Sintering
The aim of this project is to develop inexpensive sorbents for CO2 to work within an efficient thermodynamic cycle. Dr Zili Zhang of Imperial College London gave the update on the project with a presentation titled “Advanced Sorbent via Controlled Sintering of Natural Calcium-Sorbent for Carbon Capture”. The calcium looping process was explained and its key advantages were enumerated. The process is reversible, extracting CO2 from gas of low concentration of CO2 and provides a gas stream of high concentration of CO2. However, a major setback of this process for CCS was highlighted as the diminishing long term CO2 capture capability mainly due to sintering. According to the presentation, two methods for improving the long term capacity of the sorbent are thermal pre-treatment and doping natural limestone particles with HBr and HCl.
The presentation was based on the experimental work done by the investigators to determine whether pre-treatment can improve reactivity under realistic conditions, and when combined with doping techniques. Experimental results were presented of capacity enhancement with pre-treatment only and pre-treatment plus doping techniques under various realistic conditions. Conditions tested included: pre-treatment only with varying gas composition, pre-treatment only with varying temperature under CO2, pre-treatment plus doping under N2 and pre-treatment plus doping under CO2. It was concluded that pre-treatment under CO2 helps to stabilise the sample in the long term through self-reactivation at a cost of low initial reactivity of the sorbent. Also doping could also lead to self-reactivation as a result of improved regeneration, but also at a cost of low initial reactivity of the sorbent. The final conclusion was that doping and pre-treatment both improve sorbent residual capacity under realistic cycling conditions, but the effect of pre-treatment is relatively small.
Novel Reductive Rejuvenation Approaches for Degraded Amine Solutions from PCC in Power Plants
The aim of this project is to investigate novel reductive approaches for rejuvenating spent amine solutions from PCC plants, namely selective catalytic hydro-treatments at modest temperatures and H2 pressures and hydrous pyrolysis (hydrothermal conversion). Dr Chenggong Sun of the University of Nottingham provided an update for this Call 2 project with a presentation titled “Reductive Approaches for the Rejuvenation or Conversion into Value-added Products of Degraded Amine Solvents from PCC in Power Plants: An Exploratory Study”. General background information was given on amine-based CO2 capture systems and degradation of amine in CO2 capture. Even though amine scrubbing is the best available capture technology, amine sorbents are susceptible to severe thermal and oxidation degradation, leading to reduced capture efficiency and challenges of handling large quantities of toxic waste. Also amine degradation leads to the presence of acidic gases leading to formation of heat stable salts.
The presentation provided an update on work done by the project investigators on using reductive approaches to rejuvenate degraded amine solvents or convert them into value-added products under relatively modest conditions. In the presentation, it was explained that experimental samples included six model degradation compounds and degraded amine solvents at varying degrees of degradation. Experimental methodologies involved catalytic hydro-treatments of the model compounds and solvent mixtures. Some major findings highlighted are : (1) catalytic hydrogenation and reductive hydrothermal treatments can both be effectively used to transform amine degradation products into deoxygenated products at extremely high conversion efficiencies and (2) no appreciable quantity of MEA was produced from the hydro-treatments of all samples examined so far, including both the model compounds and degraded MEA solvent samples. It was pointed out that the project was delayed due to severe lab flooding and a six month extension was granted. Future activities toward the completion of the project include hydro-treatment tests with a module continuous flow reactor to establish key process parameters. Furthermore, preliminary process assessment will be performed.