Gas-phase phosphorous poisoning of a Pt/Ba/Al2O3 NOx storage catalyst

The effect of phosphorous exposure on the NO x storage capacity of a Pt/Ba/Al 2 O 3 catalyst coated on a ceramic monolith substrate has been studied. The catalyst was exposed to phosphorous by evaporating phosphoric acid in presence of H 2 O and O 2 . The NOx storage capacity was measured before and after the phosphorus exposure and a significant loss of the NO x storage capacity was detected after phosphorous exposure. The phosphorous poisoned samples were characterized by X-ray photoelectron spectroscopy (XPS), environmental scanning electron microscopy (ESEM), N 2 -physisorption and inductive coupled plasma atomic emission spectroscopy (ICP-AES). All characterization methods showed an axial distribution of phosphorous ranging from the inlet to the outlet of the coated monolith samples with a higher concentration at the inlet of the samples. Elemental analysis, using ICP-AES, confirmed this distribution of phosphorous on the catalyst surface. The specific surface area and pore volume were significantly lower at the inlet section of the monolith where the phosphorous concentration was higher, and higher at the outlet where the phosphorous concentration was lower. The results from the XPS and scanning electron microscopy (SEM)-energy dispersive X-ray (EDX) analyses showed higher accumulation of phosphorus towards the surface of the catalyst at the inlet of the monolith and the phosphorus was to a large extent present in the form of P 4 O 10 . However, in the middle section of the monolith, the XPS analysis revealed the presence of more metaphosphate (PO 3 – ). Moreover, the SEM-EDX analysis showed that the phosphorous to higher extent had diffused into the washcoat and was less accumulated at the surface close to the outlet of the sampl

Identification and clinical implementation of biomarkers for cervical cancer

Introduction of organised screening programs and prophylactic vaccination against human papilloma virus (HPV) have successfully reduced the incidence of cervical cancer globally. In Sweden, the incidence has been reduced by about 50 % since the introduction of the national screening programme in the late 1960’s. Despite these efforts, cervical cancer is still a major cause of cancer deaths globally. In order to reduce cervical cancer, the screening program should have a high participation rate and be based on a sensitive and specific screening test. About 20 % of women in Sweden do not participate in the organised screening program, and during the last years we have also seen a rise in cervical cancer cases in Sweden among women who participate in the screening program. Thus, there is a need to develop improved screening strategies that result in a higher participation rate, and are based on tests that more precisely identify women with high risk of developing cervical cancer. This includes searching for novel biological markers (biomarkers) that can be used to more accurately identify women with a high risk of developing cervical cancer. By offering women self-sampling for HPV analysis through direct mailing of sample kits with a chemically treated paper card, the FTA card, we were able to increase the participation rate in the screening program. We also found that the use of repeated self-sampling for women that were HPV positive in the primary screening sample increased the number of women detected with higher risk of cervical cancer (Paper II). Self-sampling was shown to be non-inferior to assisted sampling by midwife (Paper III). Using this sample collection device, we further investigated the association between increased risk of cervical cancer and HPV viral load (Paper V) as well as the vaginal microbiota (Paper VI). We also showed that proteins in the vaginal fluid can be studied using self-sampling and the FTA card (Paper I). Lastly, we identified plasma proteins that are associated with cervical cancer and could represent future biomarkers (Paper IV). This thesis has provided novel aspects on the present screening strategy, explored opportunities to increase the participation rate as well as examined possible future biomarkers for screening of cervical cancer

Hydrothermally induced changes of lean NOx reduction over Cu-ZSM-5 and stability improvements by synthesis modification

The growing concern about the global warming coupled with the increasing emissions of the greenhouse gas carbon dioxide, combined with the climbing oil price, drives the interest to more fuel efficient lean combustion engines for automotive applications. Such engines require new technical solutions for reduction of NOx in the oxygen rich exhaust gases, where a conventional three-way catalyst cannot be used. One of three main techniques to reduce NOx from lean-burn engines is hydrocarbon assisted selective catalytic reduction (HC-SCR) in which hydrocarbons from the fuel are used to selectively reduce NOx in the presence of excess oxygen. A copper ion-exchanged zeolite material, Cu-ZSM-5, is one of the catalysts with the ability to perform this NOx reduction reaction. However, this material successively loses its activity in hydrothermal environment. The objective of this thesis is to investigate the catalytic changes induced by the hydrothermal environment as well as the influence of the zeolite synthesis procedure on the hydrothermal stability and on the lean NOx reduction activity of Cu-ZSM-5. By using in-situ FTIR (Fourier transform infrared) spectroscopy, the species adsorbed onto the surface during the NOx reduction reaction was observed. It was found that the reactions between molecules, in which N to C bonds were developed and rearranged in such a way that N2 could be produced, were hindered upon hydrothermal treatment of the sample. On the other hand the oxidation reactions of NO or hydrocarbons, separately, were more or less unaffected

Hydrothermally induced changes of lean NOx reduction over Cu-ZSM-5 and stability improvements by synthesis modification

The growing concern about the global warming coupled with the increasing emissions of the greenhouse gas carbon dioxide, combined with the climbing oil price, drives the interest to more fuel efficient lean combustion engines for automotive applications. Such engines require new technical solutions for reduction of NOx in the oxygen rich exhaust gases, where a conventional three-way catalyst cannot be used. One of three main techniques to reduce NOx from lean-burn engines is hydrocarbon assisted selective catalytic reduction (HC-SCR) in which hydrocarbons from the fuel are used to selectively reduce NOx in the presence of excess oxygen. A copper ion-exchanged zeolite material, Cu-ZSM-5, is one of the catalysts with the ability to perform this NOx reduction reaction. However, this material successively loses its activity in hydrothermal environment. The objective of this thesis is to investigate the catalytic changes induced by the hydrothermal environment as well as the influence of the zeolite synthesis procedure on the hydrothermal stability and on the lean NOx reduction activity of Cu-ZSM-5. By using in-situ FTIR (Fourier transform infrared) spectroscopy, the species adsorbed onto the surface during the NOx reduction reaction was observed. It was found that the reactions between molecules, in which N to C bonds were developed and rearranged in such a way that N2 could be produced, were hindered upon hydrothermal treatment of the sample. On the other hand the oxidation reactions of NO or hydrocarbons, separately, were more or less unaffected

Identification and clinical implementation of biomarkers for cervical cancer

Introduction of organised screening programs and prophylactic vaccination against human papilloma virus (HPV) have successfully reduced the incidence of cervical cancer globally. In Sweden, the incidence has been reduced by about 50 % since the introduction of the national screening programme in the late 1960’s. Despite these efforts, cervical cancer is still a major cause of cancer deaths globally. In order to reduce cervical cancer, the screening program should have a high participation rate and be based on a sensitive and specific screening test. About 20 % of women in Sweden do not participate in the organised screening program, and during the last years we have also seen a rise in cervical cancer cases in Sweden among women who participate in the screening program. Thus, there is a need to develop improved screening strategies that result in a higher participation rate, and are based on tests that more precisely identify women with high risk of developing cervical cancer. This includes searching for novel biological markers (biomarkers) that can be used to more accurately identify women with a high risk of developing cervical cancer. By offering women self-sampling for HPV analysis through direct mailing of sample kits with a chemically treated paper card, the FTA card, we were able to increase the participation rate in the screening program. We also found that the use of repeated self-sampling for women that were HPV positive in the primary screening sample increased the number of women detected with higher risk of cervical cancer (Paper II). Self-sampling was shown to be non-inferior to assisted sampling by midwife (Paper III). Using this sample collection device, we further investigated the association between increased risk of cervical cancer and HPV viral load (Paper V) as well as the vaginal microbiota (Paper VI). We also showed that proteins in the vaginal fluid can be studied using self-sampling and the FTA card (Paper I). Lastly, we identified plasma proteins that are associated with cervical cancer and could represent future biomarkers (Paper IV). This thesis has provided novel aspects on the present screening strategy, explored opportunities to increase the participation rate as well as examined possible future biomarkers for screening of cervical cancer

Studies of the influence of ZSM-5 synthesis on activity and stability of Cu-ZSM-5 in leand NOx reduction

The growing concern about the global warming coupled with the increasing emissions of the greenhouse gas carbon dioxide, combined with the climbing oil price, drives the interest to more fuel efficient lean combustion engines for automotive applications. Such engines require new technical solutions for reduction of NOx in the exhaust gases, which are in excess oxygen, where a conventional three-way catalyst cannot be used to reduce NOx. One of the three main techniques to reduce NOx from lean-burn engines is hydrocarbon assisted selective catalytic reduction (HC-SCR) in which hydrocarbons from the fuel are used to selectively reduce NOx in the presence of oxygen. A copper ion-exchanged zeolite material, Cu-ZSM-5, is one of the better catalysts for this reaction. However, this material successively looses its activity in hydrothermal environment. The objective of this thesis project is to investigate the influence of the zeolite synthesis procedure on the hydrothermal stability and on the lean NOx reduction activity of Cu-ZSM-5. By varying the aluminium source and by introducing calcium hydroxide in the ZSM-5 synthesis, Cu-ZSM-5 samples were produced, for which different NOx reduction and hydrothermal stability was observed. One of the Cu-ZSM-5 samples lost about 55% of its catalytic NOx reduction activity after aging during 12 hours in a flow of 21% O2, 1% H2O in N2, while the others lost only about 10-30%. This investigation suggests that a paired aluminium distribution in ZSM-5, created in the synthesis by using AlCl3, stabilizes the corresponding Cu-ZSM-5 in HC-SCR reactions compared with the Cu-ZSM-5 where the parent ZSM-5 is synthesised using Al(NO3)3. Introduction of calcium hydroxide in the zeolite synthesis increases in some cases, and stabilizes, the NOx reduction performance of the corresponding Cu-ZSM-5 when Al(NO3)3 is used as aluminium source. This stabilizing effect of calcium hydroxide is not observed when AlCl3 is used as aluminium source. Keywords: HC-SCR, propene, Cu-ZSM-5, hydrothermal stability, lean NOx reductio