Poly(vinyl alcohol) with sulfonic acid groups as catalyst for the alpha-pinene alkoxylation

The alkoxylation of a-pinene was carried out over poly(vinyl alcohol) containing sulfonic acid groups, as catalyst. The main product of a-pinene alkoxylation was a-terpinyl methyl ether being also formed bornyl methyl ether, fenchyl methyl ether, limonene and terpinolene as by-products. The absorption band at 1037 cm-1 in the FTIR spectrum of PVA_SSA40 (PVA membrane containing 40% of –OH groups esterified with SSA) which does not appear in the spectrum of PVA, indicates the presence of the sulfonic acid groups. The catalytic activity of PVA with sulfonic acid groups increases when the amount of sulfosuccinic acid used in the polymer crosslinking is increased from 5% to 40%. However, when the crosslinking degree increases from 20% to 40%, the conversion of a-pinene increases only slightly. Good values of selectivity to a-terpinyl methyl ether were obtained over poly(vinyl alcohol) with sulfonic acid groups. A simple kinetic model, which fits experimental concentration data quite well, was developed.

A novel Compound Elliptical-type Concentrator for parabolic primaries with tubular receiver

The Parabolic Trough (PT) is the most used concentrator in CSP (Concentrated Solar Power). However, this concentrator technology is facing a significant challenge to increase its overall efficiency and cost-effectiveness. Meanwhile, other low-cost solutions such as Fresnel concentrators are also being perceived as potentially attractive. In order to achieve the lower cost goal, new optical solutions can be considered, in parallel with improvements coming, for instance, through the use of new materials or manufacturing solutions. But conventional PTs can still be improved to yield, for instance, higher concentration values, a possible starting point for higher conversion efficiency. These new solutions, in turn, can also be useful for other technologies and applications (Fresnel Concentrators, Central Tower Receivers, etc.). However it is easier to develop and test these solutions in conjunction with parabolic primaries (continuum primary). And that is the topic of this paper: to present a new Compound Elliptical-type Concentrator for a parabolic primary with a tubular receiver. A comparison is made between this new concentrator and two other concentrators (a conventional PT concentrator and a XX SMS (Simultaneous Multiple Surface) concentrator), as well as a calculation of the total amount of collected energy (kW h) for a particular location, Faro (Portugal). The paper ends with a discussion of the results obtained, their impact and possible applications in the future.