Effective Strategies For Engaging Adult Learners

Innovative methods in teaching should be used in every college classroom to enhance student engagement, support any teaching environment and encourage inquiry among learners. Adults learn best by participation in relevant experiences and utilization of practical information. When adult students are active in their learning they are able to develop critical thinking skills, receive social support systems for the learning, and gain knowledge in an efficient way. The authors highlight several exemplary strategies for adult learners including, Think-Pair-Share, Tell -Help-Check, Give One, Get One, and the Immediate Feedback Assessment Test

n-Heptane hydroconversion over nickel-loaded aluminum- and/or boron-containing BEA zeolites prepared by recrystallization of magadiite varieties

Phase-pure [Al]BEA and [Al,B]BEA zeolites, prepared by solid-state recrystallization of synthetic aluminum-containing magadiites and conventionally synthesized [B]BEA, were tested, after ion exchange with nickel, as bifunctional catalysts for hydroconversion of n-heptane. The reducibility of nickel ions incorporated into BEA zeolites by ion exchange was investigated by temperature-programmed reduction (TPR). The acidity of the samples was characterized with strong (pyridine (Py), ammonia (NH3)) and weak (nitrogen) bases. The adsorbed bases were studied by transmission FT-IR (Py), diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy (N2), and temperature-programmed ammonia evolution (TPAE, NH3). Over Ni/H-[B]BEA the reactants were completely converted via fast hydrogenolysis, whereas this reaction pathway plays only a negligible role in the hydroconversion over Ni/H-[Al]BEA and Ni/H-[Al,B]BEA zeolites. Boron-containing BEA zeolites were less active catalysts than the boron-free catalyst in the principal unimolecular hydroconversion reactions. However, incorporation of boron into the framework of BEA zeolite results in a considerable selectivity shift towards isomerization. Results suggest that the acid strength of bridged hydroxyls, probed with weak (N2) and strong basis (pyridine), was found to be similar in the boron-free and boron-containing BEA samples. The decrease in the isomerization rate and the increase of the apparent activation energy upon incorporation of boron may be attributed to the decrease in the heat of n-heptane adsorption

Investigation of acid properties of dealuminated H-mordenite zeolites by low-temperature diffuse reflectance FTIR

A series of dealuminated hydrogen mordenites (total Si/Al = 7.7, 11.6, 16.8, 29.0, 39.0) were investigated by diffuse reflectance IR spectroscopy with and without probe molecules (CO, H2). In the stretching vibration region of the pure samples bands were observed at 3613–3611, 3734, 3675 and 3510 cm–1 at room temperature and assigned to bridging OH groups [νAl(OH)Si], silanol groups (νSiOH), OH of Al-containing species partially coordinated to the framework and hydrogen-bonded SiOH species in highly dealuminated specimens, respectively. When the IR spectra were obtained at 77 K, both the bands of νAl(OH)Si and νSiOH shifted to higher wavenumbers, viz. 3619 and 3740 cm–1, respectively. In the region of combination modes, bands of the pure samples were detected at 4658–4650, 4565–4552 and ca. 4500 cm–1 which could be ascribed to νAl(OH)Si+δAl(OH)Si, νSiOH+δSiOH and νSiOH+νSiO, respectively. Upon interaction with H2 or CO at 77 K the following shifts were measured: ΔνAl(OH)Si/H2= 53–63 cm–1; ΔνSiOH/H2= 5 cm–1; Δ[νAl(OH)Si+δAl(OH)Si]/H2= 24–31 cm–1; Δ(νSiOH+δSiOH)/H2= 0; ΔνAl(OH)Si/CO = 359–389 cm–1 and ΔνSiOH/CO = 102 cm–1. The intensities of the bands due to νAl(OH)Si and νAl(OH)Si+δAl(OH)Si decreased with increasing dealumination as a result of removal of acidic bridging OH groups. By contrast, the shifts Δ[νAl(OH)Si+δAl(OH)Si]/H2 and ΔνAl(OH)Si/H2 continuously increased with the degree of dealumination which is proposed to indicate a corresponding increase in the strength of the Brønsted centres, Al(OH)Si, in line with the earlier TPD results obtained with the same samples. Bands, which appeard upon H2 interaction at 77 K around 4070 and 4020 cm–1, are discussed in view of findings reported in the literature for similar systems and tentatively assigned to ‘true’ Lewis-acid sites (removable by acid leaching) and to only threefold-coordinated Al and/or Si of the framework, respectively. Finally, the bands of H2 perturbed by silanol groups (4103 cm–1), of physisorbed CO (4250 cm–1), the effect of dealumination on the formation of defects and their interaction with the probe molecules as well as the problem of the influence of CO pressure on the band shift ΔνAl(OH)Si/CO are discussed in detail