In-situ incorporation of binder during sol-gel preparation of Pd-based sulfated zirconia for reduction of nitrogen oxides under lean-burn conditions: Effect on activity and wash-coating characteristics

We have developed a dual-catalyst aftertreatment system for reducing nitrogen oxides (NOx) in the exhaust stream of natural gas-fired lean-burn engines by utilizing the unburned hydrocarbons present in the engine exhaust. The dual-catalyst bed consists of a physical mixture of a reduction catalyst (Pd/SZ) and an oxidation catalyst (Co/CeO2). In order to make this dual-catalyst system viable for practical use in the real aftertreatment units, it is necessary to develop a catalytically active washcoat for loading it onto cordierite monolith cores. To be able to handle large throughputs of gases typical of aftertreatment units, irreversible loss of activity due to separation of the wash-coat from the monolith walls can be reducedby adding binders to improve the adhesive properties of the wash-coat. However, addition of such binders may affect the catalytic activity of the resulting dual-catalyst bed. In our study, we have incorporated binders such as alumina, boehmite, bentonite or silica to the Pd/SZ catalyst using a novel technique in which the binders were added in situ during the sol-gel synthesis rather than the conventional method of adding binders (ex-situ) in catalyst slurry. Surface area analysis, X-ray diffraction (XRD) and diffuse reflectance Fourier transform spectroscopy (DRIFTS) with pyridine show that in-situ addition of binder affects the textural properties, crystal phase of zirconia and the acidic properties of the resulting Pd/SZ catalyst respectively. Electron Paramagnetic Resonance (EPR) indicated the presence of Pd+, Pd3+ and Zr3+ species in the binder-free and in situ alumina-incorporated Pd/SZ catalysts. Furthermore, steady-state activity tests on the modified dual-catalyst bed with the alumina-incorporated Pd/SZ exhibit the best performance amongst the other binder-incorporated catalysts in the dual-catalyst bed. In-situ incorporation of binder during sol-gel synthesis yielded catalysts with far superior catalytic activity for NOx reduction than conventional ex-situ binder addition to the catalyst slurry for wash-coating. Time-on-stream experiments show that the alumina-incorporated Pd/SZ catalyst maintains the hydrothermal stability of the binder-free Pd/SZ in the mixed bed. Several parameters such as pH of the binder-incorporated catalyst slurry and calcination temperature of the wash-coat have also been optimized to develop a catalytically active wash-coat and its adhesivity and uniformity were tested using ultrasonication, cyclic thermal shock and SEM imaging. (C) 2016 Elsevier B.V. All rights reserved

The prevalence of microalbuminuria and relevant cardiovascular risk factors in Turkish hypertensive patients

Objectives: A growing body of data illustrates the importance of microalbuminuria (MAU) as a strong predictor of cardiovascular risk in the hypertensive population. The present study was designed to define the prevalence of MAU and associated cardiovascular risk factors among Turkish hypertensive outpatients. Study design: Representing the Turkish arm of the multinational i-SEARCH study involving 1,750 sites in 26 countries around the world, a total of 1,926 hypertensive patients from different centers were included in this observational and cross-sectional survey study. Patients with reasons for a false-positive MAU test were excluded. The prevalence of MAU was assessed using a dipstick test, and patients were inquired about comorbidities, comedication, and known cardiovascular risk factors. Results: The overall prevalence of MAU was 64.7% and there was no difference between genders. Most of the patients (82.5%) had uncontrolled hypertension, 35.6% had dyslipidemia, and 35.5% had diabetes, predominantly type 2. Almost one-third of the patients (26.4%) had at least one cardiovascular-related comorbidity, with 20.3% having documented coronary artery disease (CAD). Almost all patients (96.8%) had one or more risk factors for cardiovascular disease in addition to hypertension, including family history of myocardial infarction or CAD, diabetes, dyslipidemia, lack of physical exercise, and smoking. A trend towards higher MAU values in the presence of CAD was determined. Conclusion: Microalbuminuria tests should be routinely used as a screening and monitoring tool for the assessment of subsequent cardiovascular morbidity and mortality among hypertensive patients. © 2011 Turkish Society of Cardiology

The prevalence of microalbuminuria and relevant cardiovascular risk factors in Turkish hypertensive patients.

Objectives: A growing body of data illustrates the importance of microalbuminuria (MAU) as a strong predictor of cardiovascular risk in the hypertensive population. The present study was designed to define the prevalence of MAU and associated cardiovascular risk factors among Turkish hypertensive outpatients. Study design: Representing the Turkish arm of the multinational i-SEARCH study involving 1,750 sites in 26 countries around the world, a total of 1,926 hypertensive patients from different centers were included in this observational and cross-sectional survey study. Patients with reasons for a false-positive MAU test were excluded. The prevalence of MAU was assessed using a dipstick test, and patients were inquired about comorbidities, comedication, and known cardiovascular risk factors. Results: The overall prevalence of MAU was 64.7% and there was no difference between genders. Most of the patients (82.5%) had uncontrolled hypertension, 35.6% had dyslipidemia, and 35.5% had diabetes, predominantly type 2. Almost one-third of the patients (26.4%) had at least one cardiovascular-related comorbidity, with 20.3% having documented coronary artery disease (CAD). Almost all patients (96.8%) had one or more risk factors for cardiovascular disease in addition to hypertension, including family history of myocardial infarction or CAD, diabetes, dyslipidemia, lack of physical exercise, and smoking. A trend towards higher MAU values in the presence of CAD was determined. Conclusion: Microalbuminuria tests should be routinely used as a screening and monitoring tool for the assessment of subsequent cardiovascular morbidity and mortality among hypertensive patients. © 2011 Turkish Society of Cardiology