For chemical recycling of waste plastics, HZSM-5, HY, and H-mordenite zeolites and silica−alumina were examined as catalysts for the degradation of polyethylene in a fixed-bed flow reactor system, and their activities and deactivation behaviors caused by coke deposition were studied. HZSM-5 catalyst was found to be very effective for the production of gasoline-range fuel oils mainly consisting of isoparaffins and aromatics and showed no deactivation due to a very low yield of coke deposited on the catalyst surface, whereas in the degradation of polystyrene a marked deactivation was observed (Uemichi et al. Kobunshi Ronbunshu 1993, 50, 887). Silica−alumina gradually deactivated as time on stream increased, but the degree of deactivation was less than expected from the deposition of a significant amount of coke, probably because the coke deposition in the large pores of the catalyst caused no marked influence on the diffusion of the decomposed fragments involved in the reaction. On the other hand, deactivations of HY and H-mordenite were striking; the latter was most abruptly deactivated, resulting in a marked decrease in the liquid yield. From the surface area measurements of the used catalysts, it was suggested that the pores of HY were sufficiently filled out with coke, while pore blocking by coke occurred in the unidimensional channels of H-mordenite.

Economic growth requires that firms adopt new technologies. However, it may be insufficient in less competitive industries from the social welfare point of view. In this case, a government subsidy is necessary. We present an analysis of firms' adoption of new technology and government subsidization policy in a Stackelberg duopoly with differentiated goods. The technology itself is free, but each firm must expend a fixed set-up cost, such as training employees. There are several cases related to optimal policies depending on the set-up costs and whether the goods are substitutes or complements. In particular, there are two cases.1. Social welfare is maximized when only the Stackelberg leader adopts the new technology, but no firm adopts the new technology without a subsidy. Then, the government should subsidize only the leader, which is a discriminatory policy. (Case 5 of Theorem 1 and Case 3-(1)-ii of Theorem 2) 2. Social welfare is maximized when both firms adopt the new technology, but only the leader adopts the new technology without a subsidy. Then, the government should subsidize only the follower. This policy is not discriminatory because adoption is the dominant strategy for the leader. (Case 2 of Theorem 1)

We consider choice of options for a foreign innovating firm to license its technology for producing the high quality good to a domestic firm, or to enter the market of the domestic country with or without license. Under the assumption of uniform distribution about taste parameters of consumers; when cost functions are linear, if the low quality good's quality is sufficiently high, license without entry strategy is optimum; if the low quality good's quality is low, both of entry without license strategy and license without entry strategy are optimum; when cost functions are quadratic, if the high quality good's quality is high, license without entry strategy is optimum; if the high quality good's quality is low, entry with license strategy is optimum.

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We consider a problem of subsidy or tax policy for new technology adoption by duopolistic firms. The technology is developed in and transferred by a foreign country to the domestic country. It is free but each firm must expend some fixed set-up cost for education of its staff to adopt and use it. Assuming that each firm maximizes the weighted average of absolute and relative profits, we examine the relationship between competitiveness and subsidy or tax policies for technology adoption, and show that when firm behavior is not competitive (the weight on the relative profit is small), the optimal policy of the government may be taxation; when firm behavior is competitive (the weight on the relative profit is large), the optimal policy is subsidization or inaction and not taxation. However, if firm behavior is extremely competitive (close to perfect competition), taxation case re-emerges.