Renewable resources and bio-based feedstocks may present a sustainable alternative to petrochemical sources to satisfy modern society's ever-increasing demand for energy and chemicals. However, the conversion processes needed for these future bio-refineries will likely differ from those currently used in the petrochemical industry. Biotechnology and chemocatalysis offer routes for converting biomass into a variety of molecules that can serve as platform chemicals. While a host of technologies can be leveraged for biomass upgrading, condensation reactions are significant because they have the potential to upgrade these bio-derived feedstocks while minimizing the loss of carbon and the generation of by-products. This review surveys both the biological and chemical catalytic routes to producing platform chemicals from renewable sources and describes advances in condensation chemistry and strategies for the conversion of these platform chemicals into fuels and high-value chemicals.

starch or sugar-rich biomass (corn (maize), other cereals, sugar cane, etc.) into sugar, fermentation, and distillation. Advanced process: hydrolysis of ligno-cellulosic biomass, fermentation and distillation. Biodiesel production: extraction and esterification of vegetable oils, used cooking oils and animal fats using alcohols. Advanced processes: hydrogenation of oil and fat; gasification and catalytic conversion to liquid fuels (biomass to liquid, BTL). Biomethane: biogas from anaerobic digestors and landfills used as compressed gas in natural gas vehicles. ENERGY INPUT AND EMISSIONS -Because of the variety of feedstocks and processes, figures vary widely and make it difficult to identify indicative values. Sugar-cane ethanol: fossil fuel input some 10%-12% of final energy and up to 90% CO 2 reduction compared with gasoline. Corn ethanol: high energy input and much smaller CO 2 reduction (15-25%). Ligno-cellulosic ethanol: total energy input may be higher than for corn ethanol, but most such energy could be provided from biomass itself, with CO 2 reduction up to 70% (100% with power co-generation). Biodiesel: about 30% energy input and up to 60% CO 2 reduction. COSTS -High sensitivity to feedstock, process, land type and crop yield. BARRIERS -Competition with food and fibre production for use of arable land; cost; regional market structure; biomass transport; lack of well managed agricultural practices in emerging economies; water and fertiliser use; conservation of bio-diversity; logistics and distribution networks. PROCESS -Bioethanol conventional production -Bioethanol is the most common biofuel, accounting for more than 90% of total biofuel usage. Conventional production is a well known process based on enzymatic conversion of starchy biomass into sugars, and/or fermentation of 6-carbon sugars with final distillation of ethanol to fuel grade. Ethanol can be produced from many feedstocks, including cereal crops, corn (maize), sugar cane, sugar beets, potatoes, sorghum, cassava. Coproducts (e.g animal feed) help reduce production cost. If sugar cane is used, conversion into sugar is easier. Crushed stalk (bagasse) can be used to provide heat and power for the process and for other energy applications. The world's largest producers of bio-ethanol are Brazil (sugar-cane ethanol) and the United States (corn ethanol). Ethanol is used in low 5%-10% blends with gasoline (E5, E10) but also as E-85 in flex-fuel vehicles. In Brazil, gasoline must contain a minimum of 22% bioethanol.Bioethanol advanced productionWhile conventional processes use only the sugar and starch biomass components, R&D focuses on advanced processes that utilise the all available ligno-cellulosic materials. These processes hold the potential to increase variety and quantity of suitable feedstock including cellulosic wastes, maize stover, cereal straw, foodprocessing wastes, as well as dedicated fast-growing plants such as poplar trees and switch-grass. Cellulosic feedstock could be grown on non arable land or be produced from integrated crops,...

A novel hierarchically porous, hyper-cross-linked siloxane-organic hybrid (PSN-5) has been synthesized by Friedel-Crafts self-condensation of benzyl chloride-terminated double-four-ring cubic siloxane cages as a singular molecular precursor. Simultaneous polymerization of the organic functional groups and destruction of the siloxane cages during synthesis yielded PSN-5, which has an ultrahigh BET surface area (∼2500 m(2) g(-1)) and large pore volume (∼3.3 cm(3) g(-1)) that to our knowledge are the highest values reported for siloxane-based materials. PSN-5 also shows a high H(2) uptake of 1.25 wt % at 77 K and 760 Torr.