Howard L. Greene

Bio: Howard L. Greene is an academic researcher from Case Western Reserve University. The author has contributed to research in topics: Catalysis & ZSM-5. The author has an hindex of 6, co-authored 6 publications receiving 1254 citations.

Generating hydrogen-rich fuel-cell feeds from dimethyl ether (DME) using physical mixtures of a commercial Cu/Zn/Al2O3 catalyst and several solid-acid catalysts

Abstract: Homogeneous physical mixtures containing a commercial Cu/ZnO/Al2O3 catalyst and a solid–acid catalyst were used to examine the acidity effects on dimethyl ether hydrolysis and their subsequent effects on dimethyl ether steam reforming (DME-SR). The acid catalysts used were zeolites Y [Si/Al = 2.5 and 15: denoted Y(Si/Al)], ZSM-5 [Si/Al = 15, 25, 40, and 140: denoted Z(Si/Al)] and other conventional catalyst supports (ZrO2, and γ-Al2O3). The homogeneous physical mixtures contained equal amounts, by volume, of the solid–acid catalyst and the commercial Cu/ZnO/Al2O3 catalyst (BASF K3-110, denoted as K3). The steam reforming of dimethyl ether was carried out in an isothermal packed-bed reactor at ambient pressure. The most promising physical mixtures for the low-temperature production of hydrogen from DME contained ZSM-5 as the solid–acid catalyst, with hydrogen yields exceeding 90% (T = 275 °C, S/C = 1.5, τ = 1.0 s and P = 0.78 atm) and hydrogen selectivities exceeding 94%, comparable to those observed for methanol steam reforming (MeOH-SR) over BASF K3-110, with values equaling 95% and 99%, respectively (T = 225 °C, S/C = 1.0, τ = 1.0 s and P = 0.78 atm). Large production rates of hydrogen were directly related to the type of acid catalyst used. The hydrogen production activity trend as a function of physical mixture was K 3 + Z ( 25 ) K 3 + Z ( 15 ) K 3 + Z ( 40 ) > K 3 + Z ( 140 ) K 3 + Y ( 15 ) > K 3 + Y ( 2.5 ) ≫ K 3 + γ -A l 2 O 3 > K 3 + Zr O 2

Generating hydrogen-rich fuel-cell feeds from dimethyl ether (DME) using Cu/Zn supported on various solid-acid substrates

Abstract: Several incipient wetness prepared catalysts containing copper and zinc were prepared in-house and reactor tested for the production of hydrogen from dimethyl ether steam reforming (DME-SR). The incorporation of copper and zinc onto a solid acid substrate (viz., zeolites ZSM-5 and Y with Si/Al = 2.5–140, g-Al2O3, and ZrO2) combined the catalytic components for DME hydrolysis to methanol (MeOH) and methanol steam reforming (MeOH-SR) into a single catalyst. Catalyst characterizations included BET surface areas, metal loading, acidity measurements using isopropyl amine, thermogravimetric uptakes of DME, and X-ray diffraction studies. One co-ion exchange sample was tested and was found to be inactive toward DME-SR because of its inactivity toward methanol steam reforming. The most active catalyst was copper–zinc supported on g-Al2O3, reaching an equilibrium predicted hydrogen yield of 89% (steam-to-carbon ratio (S/C) = 1.5, space-time(t) = 1.0 s, T = 400 8C, and Pabs = 0.78 atm). Of the zeolite-supported Cu/Zn catalysts, copper–zinc supported on zeolite ZSM-5 with a Si–Al ratio of 25 was observed to be the most active with a hydrogen yield of 55% (S/C = 1.5, t = 1.0 s, T = 275 8C, and Pabs = 0.78 atm). # 2006 Elsevier B.V. All rights reserved.

Role of acidity on the hydrolysis of dimethyl ether (DME) to methanol

Abstract: The activity of dimethyl ether (DME) hydrolysis was investigated over a series of solid acid and non-acid catalysts, zeolite Y [Si/Al = 2.5 and 15: denoted Y(Si/Al)], zeolite ZSM-5 [Si/Al = 15, 25, 40, and 140: denoted Z(Si/Al)], silica, zirconia, γ-alumina, and BASF K3-110 (commercial Cu/ZnO/Al 2 O 3 catalyst). Dimethyl ether hydrolysis was carried out in an isothermal packed-bed reactor at ambient pressure. Acid catalyzed dimethyl ether hydrolysis is equilibrium limited. All solid acid catalysts, with the exception of ZrO 2 , attained equilibrium-limited conversions in the temperature range of interest (125–400 °C). Z(15), Z(25), and Z(40) reached equilibrium conversions at 200 °C, while Z(140), Y(15), and Y(2.5) reached equilibrium at 275 °C. γ-Alumina, the most active non-zeolite solid acid, attained equilibrium at 350 °C. Silica and BASF K3-110 were both ineffective in converting dimethyl ether to methanol. The observed activity trend for DME hydrolysis to methanol as a function of Si–Al ratio and catalyst type was: Z ( 15 ) Z ( 25 ) Z ( 40 ) > Z ( 140 ) Y ( 15 ) > Y ( 2.5 ) ≫ γ -A l 2 O 3 > Zr O 2 .

Trichloroethylene sorption and oxidation using a dual function sorbent/catalyst in a falling furnace reactor

Abstract: A dual function zeolite medium (Cr-ZSM-5), capable of physisorbing trichloroethylene (TCE) at ambient temperature and catalytically oxidizing it at elevated temperature (∼350°C), was utilized in a novel continuous falling furnace reactor system to store and periodically destroy this chlorinated volatile organic compound. For inlet feed streams between 50 and 1600 ppm of TCE in humid air, overall destruction levels were typically above 99%. Also, since the falling furnace system required heating only during the desorption/reaction portion of the process (5–10% of the cycle time), energy comparison with conventional catalytic reactors is extremely favorable.

Recent advances in catalytic hydrogenation of carbon dioxide

Abstract: Owing to the increasing emissions of carbon dioxide (CO2), human life and the ecological environment have been affected by global warming and climate changes. To mitigate the concentration of CO2 in the atmosphere various strategies have been implemented such as separation, storage, and utilization of CO2. Although it has been explored for many years, hydrogenation reaction, an important representative among chemical conversions of CO2, offers challenging opportunities for sustainable development in energy and the environment. Indeed, the hydrogenation of CO2 not only reduces the increasing CO2 buildup but also produces fuels and chemicals. In this critical review we discuss recent developments in this area, with emphases on catalytic reactivity, reactor innovation, and reaction mechanism. We also provide an overview regarding the challenges and opportunities for future research in the field (319 references).

Recent Advances in the Catalytic Oxidation of Volatile Organic Compounds: A Review Based on Pollutant Sorts and Sources.

Abstract: It is well known that urbanization and industrialization have resulted in the rapidly increasing emissions of volatile organic compounds (VOCs), which are a major contributor to the formation of secondary pollutants (e.g., tropospheric ozone, PAN (peroxyacetyl nitrate), and secondary organic aerosols) and photochemical smog. The emission of these pollutants has led to a large decline in air quality in numerous regions around the world, which has ultimately led to concerns regarding their impact on human health and general well-being. Catalytic oxidation is regarded as one of the most promising strategies for VOC removal from industrial waste streams. This Review systematically documents the progresses and developments made in the understanding and design of heterogeneous catalysts for VOC oxidation over the past two decades. It addresses in detail how catalytic performance is often drastically affected by the pollutant sources and reaction conditions. It also highlights the primary routes for catalyst deactivation and discusses protocols for their subsequent reactivation. Kinetic models and proposed oxidation mechanisms for representative VOCs are also provided. Typical catalytic reactors and oxidizers for industrial VOC destruction are further discussed. We believe that this Review will provide a great foundation and reference point for future design and development in this field.

Recycling of carbon dioxide to methanol and derived products – closing the loop

Abstract: Starting with coal, followed by petroleum oil and natural gas, the utilization of fossil fuels has allowed the fast and unprecedented development of human society. However, the burning of these resources in ever increasing pace is accompanied by large amounts of anthropogenic CO2 emissions, which are outpacing the natural carbon cycle, causing adverse global environmental changes, the full extent of which is still unclear. Even through fossil fuels are still abundant, they are nevertheless limited and will, in time, be depleted. Chemical recycling of CO2 to renewable fuels and materials, primarily methanol, offers a powerful alternative to tackle both issues, that is, global climate change and fossil fuel depletion. The energy needed for the reduction of CO2 can come from any renewable energy source such as solar and wind. Methanol, the simplest C1 liquid product that can be easily obtained from any carbon source, including biomass and CO2, has been proposed as a key component of such an anthropogenic carbon cycle in the framework of a “Methanol Economy”. Methanol itself is an excellent fuel for internal combustion engines, fuel cells, stoves, etc. It's dehydration product, dimethyl ether, is a diesel fuel and liquefied petroleum gas (LPG) substitute. Furthermore, methanol can be transformed to ethylene, propylene and most of the petrochemical products currently obtained from fossil fuels. The conversion of CO2 to methanol is discussed in detail in this review.