HP Quad Series Micro GCs The rugged, high-speed HP Quad Series micro GCs are designed to analyze the most complex gas samples, providing unsurpassed speed of analysis, great flexibility and remarkable durability. The HP Quad Series is ideal for applications that require multiple columns at different settings, multiple sample inlets or more than one carrier gas. It can be configured as a laboratory or portable unit. For more information and detailed specifications, click here.

IF THE PETROLEUM industry selects catalysts to improve the performance of their refineries, what do catalyst makers use to help achieve this purpose?

In the case of Akzo-Nobel, they use HP Quad Series micro GCs.

Akzo-Nobel is a world leader in the production of petrochemical catalysts. Their operation in Houston includes research and tech service facilities, where they continually attempt to improve their products for various applications. Technical service also includes helping customers choose the catalyst appropriate to the sample of feedstock they have submitted.

The nature of catalysts is such that analyzing them for their chemical composition is insufficient to the task of determining their effectiveness. Their physical characteristics--such as their surface area, measured in m²/gram--are a determining factor in their effectiveness. But even when you know that, you still don't know how the catalyst will perform with any given feedstock. The only way to find out is to do a trial run of the feed and the catalyst through the refining process. But that approach is prohibitively expensive.

Accordingly, to provide a catalyst characterization service to both internal customers--the research group--and external customers alike, Akzo-Nobel operates a small FCC pilot plant. "FCC" stands for fluidized catalytic cracker, which is the process used by refiners to crack long chains of hydrocarbons into smaller chains. It's how refiners produce gasoline and other petrochemical products from crude oil.

The FCC circulates catalyst through the process continuously. To maintain a stable level of catalyzing material, a relatively small portion of old catalyst is removed from the cracker at relatively short intervals and replenished with new catalyst. "Relatively" is the operative word here: at their Gulf Coast plant, for example, one major refinery replenishes 20 tons of catalyst a day.

Similarly, Akzo-Nobel's pilot plant is only relatively small. Small by refinery standards, perhaps, it nevertheless rises three stories and is certainly not small by, say, Lego standards.

At Akzo-Nobel, Assistant Chemist Clark Rea runs the sample du jour through his pilot FCC plant and samples the gas stream at the output of the process. If it's a new catalyst formulation from the research side of the house, he'll look for changes to product yield. If it's a new feed from an external customer, he'll run it over three or four catalysts to see which produces the best yield.

An on-line laboratory

"They are actually monitoring the outgases from these reactions as they are occurring," notes Chuck Runkle, HP's micro-GC specialist in Austin Texas. "It's not a process monitoring system, it's an on-line laboratory."

Up until about three years ago, Rea was using the HP 5890 gas chromatograph (GC) and similar instruments to analyze the output product. These conventional instruments used conventional packed columns and required about 45 minutes to run a sample.

"We take a catalyst and we want to characterize it," says Clark. "We usually look at it against a different catalyst. Or I'll do a study of maybe six catalysts. So I'm going to look at all six of those catalysts. Before, we were running almost blind," Rea recalls. "I'd shoot a sample and 45 minutes later I'd know what happened 45 minutes ago."

Then Rea installed the first of what is now a component of six HP Quad Series micro GCs at Akzo. The results were gratifying.

"The actual run, even with valve clean-out time and so forth, now takes only 140 seconds," says Clark. "I could shorten that to 110 and still get everything I need. I used to run maybe six or seven gas samples a day. Now I run maybe 50 or 60, and I'm not even running all the time. Instead of knowing what happened 45 minutes ago, I shoot a sample and I know what's happening now."

Rea also noted "better resolution between isobutylene and 1-butene, which is something people are interested in."

Runkle, who sold Rea his first HP Quad Series micro GC, expands on the theme. "Not only can it do an analysis in under two minutes, it costs less to operate. Takes up less space. And cost of ownership is lower. It uses less carrier gas and electricity and uptime is good because you don't have the problems associated with standard gas sample valves, with leaks, rotors being broken that need to be replaced, all the things that happen to mechanical devices."

Rea concurs. "Our maintenance is virtually non-existent," he says.

HP uses silicon technology to make the gas sample valve and detector. With precision micro-machining technology, the injection valves have a demonstrated reliability of more than 2.5 million analysis cycles with no signs of wear.

What makes the HP Quad Series micro GC so fast is the volumes being analyzed. One microliter to 0.4 microliter of analyte is injected, and the detector volume is <200 nanoliters.

Concludes Clark Rea, "The bottom line is, I'm characterizing better. I know what's happening every couple minutes."